For a transfer window that's endlessly 'difficult to do business in' according to just about every football manager ever, a fair bit of transfer business gets pushed through every year.

None more so than in the Premier League, where if it's not lower down sides desperately trying to bolster their roster in fear of relegation, it's top sides looking for the marginal gains that can set them up nicely for the future.

In and amongst that chaos, it does actually prove difficult to do good business in January. That's why when a club nails it, we know about it. Be it a short-term fix or a long-term setup, planning has to be meticulous to ensure a mid-season signing isn't a waste of time and money.

Here at GIVEMESPORT, we've pulled together the top 14 bits of January business to be conducted in the Premier League.

16. Christophe Dugarry - Bordeaux to Birmingham City (2003)

With Birmingham stranded in a relegation scrap in the 2002/03 season and desperate to retain their Premier League status, they believed the answer to their prayers was an ageing World Cup winner, looking for one last hurrah. And it was. Christophe Dugarry packed his bags and left his native France to head to the Midlands, and hit it off instantly. His five goals in four games propelled Birmingham away from danger and helped them to a 13th place finish. It all went downhill the moment he signed a permanent deal, but his instant contribution earned him a place in the club's hall of fame.

15. Tomas Soucek - Slavia Prague to West Ham (2020)

In a year that would only get stranger and stranger very quickly, West Ham signing apparent nobodies in a bid to salvage their campaign under David Moyes felt somewhat normal. Tomas Soucek might not have been a name many Hammers fans were familiar with, but his presence was felt immediately in their midfield. The Czech Republic captain took to England immensely well, becoming a mainstay in the starting XI as a goal threat from deep, before signing permanently and helping propel the Hammers to dizzy new heights of European football. Absolute bargain.

Tomas Soucek celebrates for West Ham. (Photo by Adam Davy - Pool/Getty Images)

14. Ashley Young - Watford to Aston Villa (2007)

Having come through the ranks at Watford, 2006/07 was Ashley Young's breakout season, where it became apparent he was capable of plying his trade higher up the Premier League. A bidding war ensued that January, but it was Aston Villa who snapped up the exciting and direct winger. They enjoyed four years of his service at Villa Park where he only continued to excel, bagging goals and assists in a chase for European football, before Manchester United came calling. A very important signing.

13. Jermain Defoe - Toronto to Sunderland (2015)

Just 11 months into a four-year deal with Toronto, Jermain Defoe was coaxed back to England by the prospect of joining relegation-threatened Sunderland in the January of 2015. He headed to the North East with Jozy Altidore going the other way and proved an instant fan favourite; not surprising for a player of his calibre. Among the array of goals he scored to keep them up was an absolute scorcher against Newcastle to win the Tyne-Wear derby. He enjoyed a prolific two years with Sunderland and was an obvious fan favourite.

Jermain Defoe scores against Liverpool. (Photo by Stu Forster/Getty Images)

12. Clint Dempsey - New England Revolution to Fulham (2007)

It's a gamble, is the MLS. Perhaps less so nowadays, but certainly in 2007. Fulham made Clint Dempsey their third American in the squad and, at the time, the most expensive MLS signing ever when he joined the club in January 2007. It took him a while to click, but his first goal in May proved vital as it kept the Cottagers in the Premier League, and was the start of an emphatic five-year stay that saw the striker rise to the challenge of the English top flight.

11. Luis Diaz - Porto to Liverpool (2022)

Attracting interest from plenty of suitors throughout Europe, including Premier League rivals Tottenham, Liverpool changed their transfer plans and parted with an initial £37.5 million to sign Luis Diaz in January. It felt a touch risky, and not very Liverpool of recent years to scrap their initial transfer strategy and spend big, but boy does it look to be paying off. The Colombian has settled into Jurgen Klopp's side seamlessly, bringing his goal threat and jaw-dropping skillset to the Premier League already. He hasn't been here long, but Diaz looks destined to become a world-beater with Liverpool.

Luis Diaz has settled in quickly at Liverpool. (Photo by Shaun Botterill/Getty Images)

Jurien Timber opens talks with Manchester United (Football Terrace)

10. Christian Eriksen - Inter to Brentford (2022)

Technically, Christian Eriksen arrived at Brentford as a free agent, but this was due to Inter having to release the Dane as he was no longer able to play in Italy after being fitted with an implantable cardioverter-defibrillator. Brentford were a surprise candidate but won the race for Eriksen, which has proven massive to their Premier League campaign. The 30-year-old's experience and technical excellence have given a new lease of life to the side, who now look set for another season in the top flight, thanks to his creative impact. Keeping hold of him beyond the end of the season could prove difficult.

9. Jose Antonio Reyes - Sevilla to Arsenal (2004)

To make an impact in an Arsenal side that was set to become invincible domestically is a task, not least as a young Spaniard arriving halfway through the season. Jose Antonio Reyes did exactly that, though, proving why he was worth every bit of the £17m he cost in January. His goals helped to knock Chelsea out of the FA Cup and the Champions League, before also firing to help Arsenal win the Premier League while going unbeaten. The late, great Reyes returned to Spain in 2006 after plenty of speculation, but no doubt would've continued to blossom had he stayed in England.

Reyes scored a number of key goals immediately for Arsenal. (Photo by Phil Cole/Getty Images)

8. Pierre-Emerick Aubameyang - Borussia Dortmund to Arsenal (2018)

Speculation linking Pierre-Emerick Aubameyang with a move away from Dortmund had been rife for some time by this point, but it was the Gunners who bit the bullet, stumping up a club-record fee to bring him to London on the final day of the January transfer window. Ten goals and four assists from 13 games in that half a season proved just how ruthless a finisher he was. Aubameyang very swiftly made his mark, sharing the Golden Boot award in 2018/19 with Mohamed Salah and Sadio Mane, and winning the FA Cup in 2020, before an unfortunately soured exit in 2022.

7. Nemanja Matic - Benfica to Chelsea (2014)

Having already failed to break in properly once at Chelsea, it showed just how much Nemanja Matic had developed to see the Blues pay £21m to Benfica in the January of 2014, to bring him back to Stamford Bridge. Now slightly older, a lot wiser and having played plenty of games at a top side, the Serbian had transitioned into the ideal defensive midfielder. Putting in a man of the match display against Manchester City upon his return set the tone for a splendid three-year stay, where he played a key role in winning two Premier League titles.

Nemanja Matic re-joined Chelsea in 2014. (Photo by Jordan Mansfield/Getty Images)

6. Bruno Fernandes - Sporting CP to Manchester United (2020)

Having been linked with him all summer long in 2019, it felt pretty inevitable that Manchester United would go back in for Bruno Fernandes at the first possible opportunity. And with their attack drying up tremendously, he arrived at just the right time. Fernandes racked up 11 goals and eight assists from 19 games in all competitions for United in the second half of the season, going on a complete tear and becoming the lynchpin and winning the Sir Matt Busby Player of the Year award that September.

5. Philippe Coutinho - Inter to Liverpool (2013)

Struggling for game time in Italy, Liverpool spotted potential in a young Philippe Coutinho and were willing to pay £8.5m to free him from Inter mid-season. Rafael Benitez assured his former club that the Brazilian would become 'world class', which proved a fair assessment. Coutinho showed glimpses of that ceiling over the next year or so, before becoming a consistently elite component for Liverpool and arguably the best playmaker in the world, tempting Barcelona to part with £105m to bring him to Camp Nou in January 2018.

Coutinho was bought and sold by Liverpool in January windows. (Photo by Jan Kruger/Getty Images)

4. Luis Suarez - Ajax to Liverpool (2011)

The man who Coutinho would form a sublime partnership within Merseyside, Luis Suarez signed from Ajax on the final day of the transfer window in a club-record fee. While that fee was then broken by the arrival of fellow striker Andy Carroll just hours later, it was Suarez who stepped up to replace the Fernando Torres-shaped hole, helping Liverpool go from 12th to sixth in his first few months. His controversies never put off any potential suitors, and in 2014, the Reds sold the Uruguayan for almost £65m to Barcelona, despite him serving a four-month football ban. Just too good to resist.

3. Patrice Evra - Monaco to Manchester United (2006)

Recruited by Sir Alex Ferguson to bolster the left-back role with Gabriel Heinze out of action, Patrice Evra was snapped up by Manchester United early in the January window, amid interest from rival clubs. Evra struggled to adapt initially, and continued to rotate in and out of the XI heading into 2006/07, but had cemented his place after a year or so of adaptation. From then on, the Frenchman blossomed, becoming a key piece to the puzzle as United dominated domestically and reached the European summit once more. Eight years, five Premier Leagues, one Champions League, three League Cups and then some. Sublime.

Patrice Evra captains Manchester United. (Photo by Clive Mason/Getty Images)

2. Virgil van Dijk - Southampton to Liverpool (2018)

Spending £75m on any player is a rather large risk, not least when you're Liverpool, on the cusp of becoming a truly top side once again after lots of meticulous strategy. To put all that money down on Virgil van Dijk was seen as too big a risk by some, but the reward has been immense and endless. The Dutchman marked his Liverpool debut with a headed goal against Everton, and immediately looked like a world record-setting defender, having left Southampton. He's now forging a legacy as one of the Premier League's best, having been integral to Premier League and European success.

1. Nemanja Vidic - Spartak Moscow to Manchester United (2006)

After reportedly being interested in him for over two years, Manchester United finally snapped up Nemanja Vidic in January 2006, having agreed a £7m fee on Christmas day, ahead of the transfer window., hijacking Fiorentina's agreement that had stalled. That hijacking would be key to United's fortunes over the next decade or so, as Vidic formed arguably the greatest centre back partnership in the Premier League with Rio Ferdinand, blossoming into the ultimate defender. Aggressive and physical but also tactically tuned, Vidic served as club captain and was integral to five Premier League wins, a Champions League and plenty more silverware, alongside Evra.

Manchester United swooped in for Vidic in January 2006. (Photo by Alex Livesey/Getty Images)