Sir Alex Ferguson is the greatest manager of all-time.

He had an incredible amount of success during his 27-year stint with Manchester United.

The Scotsman won 38 trophies, including 13 Premier League titles and two Champions League's.

The success he had in England's top tier will likely never be replicated.

During his spell with Man United, Ferguson spent hundreds of millions of pounds in his quest to win trophies.

But, despite being the greatest manager ever, he didn't always spend wisely.

Transfermarkt have listed his 25 most expensive transfer during his career. We've taken a look at the list and given each of these signings a rating out of 10.

The fee each player was signed for, as well as their success during their time at the club, were both taken into account.

25. Andy Cole | £8.64m

Transfer: Newcastle to Man United, December 1994

Ferguson broke a British transfer record when he signed Cole in 1995. Despite the hefty price tag, that proved to be great business.

Cole went on to score 121 goals in seven years for the club. He helped United to five Premier League titles and was part of their Champions League winning side in 1999.

Rating: 8.5/10

Andy Cole

24. Gabriel Heinze | £9m

Transfer: PSG to Man United, June 2004

Heinze was a decent player for United. He had a good first season with the club as he was named United's Player of the Year.

However, he lost his starting berth at the club to Patrice Evra and he was eventually sold for £8m in 2007.

Rating: 6/10

23. Nemanja Vidic | £9.45m

Transfer: Spartak Moscow to Man United, January 2006

What a signing. To sign one of the Premier League's best ever defenders for under £10m was a masterstroke by Ferguson.

Rating: 10/10

Manchester United v Sunderland - Premier League

22. Diego Forlan | £9.90m

Transfer: Independiente to Man United, January 2002

Forlan was a major flop. He failed to score in 18 games during his first season with the club.

Things did get slightly better for the Uruguayan, but it's fair to say he didn't live up to expectations.

Despite being a failure at United, he thrived after leaving England at Villarreal and Atletico Madrid.

Rating: 3/10

21. Fabien Barthez | £10.53m

Transfer: Monaco to Man United, June 2000

Ferguson had a nightmare trying to replace Peter Schmeichel.

Barthez's spell at United was riddled with mistakes and Ferguson finally ran out of patience in 2003.

Rating: 3/10

Fabien Barthez of Manchester United

20. Wilfried Zaha | £10.58m

Transfer: Crystal Palace to Man United, January 2013

Zaha was Ferguson's final signing as United boss.

He ended up playing just four times for Man United as he spent much of his two years out on loan.

The Ivorian has thrived at Crystal Palace since rejoining the club in 2015.

Rating: 2/10

19. Shinji Kagawa | £14.40m

Transfer: Dortmund to Man United, June 2012

Another flop. The Japanese midfielder thrived at Dortmund, convincing Ferguson to sign him for £14.40m in 2012.

He lasted just two years at the club, scoring six times in 57 games.

Rating: 3/10

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18. Jaap Stam | £15.30m

Transfer: PSV to Man United, June 1998

Stam was a beast for United. He was a regular in his first two seasons with the club, helping the club win back-to-back Premier League titles.

The Dutchman suffered an achilles injury in his third campaign and Ferguson decided to sell him for £16.50m to Lazio. Ferguson later admitted that was a mistake.

Rating: 8/10

17. Louis Saha | £15.75m

Transfer: Fulham to Man United, January 2004

Saha was decent for United, scoring 42 goals in 124 games. He never managed to establish himself a regular at the club though as he was plagued by injuries.

Rating: 6/10

Manchester United v Everton

16. Ashley Young | £16.20m

Transfer: Aston Villa to Man United, June 2011

Young started his career off at United at left-wing before being converted into a full-back.

The Englishman always gave his all but was the target of criticism during his final few years at the club.

Rating: 6/10

15. Antonio Valencia | £16.92m

Transfer: Wigan to Man United, June 2009

Like Young, Valencia started off as a midfielder but was then converted into a full-back.

He was a reliable player for United, helping them to two Premier League titles.

Rating: 6.5/10

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14. Cristiano Ronaldo | £17.10m

Transfer: Sporting CP to Man United, August 2003

Ronaldo needs no introduction. Ferguson was responsible for signing one of the best players in history for under £20m.

Rating: 10/10

13. Dwight Yorke | £17.33m

Transfer: Aston Villa to Man United, June 1998

Yorke formed a legendary partnership with Cole during his four years at Man United.

The Trinidad and Tobago striker scored 65 times in 152 games before departing for Blackburn Rovers in 2002.

Rating: 7/10

Dwight Yorke

12. Phil Jones | £17.37m

Transfer: Blackburn to Man United, June 2011

After a good start to life at the club, Ferguson famously said that Jones could become one of United's best ever players.

Jones has only gone backwards since the legendary Scottish manager retired in 2013.

Amazingly, the Englishman is still at United, although he could finally depart the club in the summer.

Rating: 4/10

11. David de Gea | £22.50m

Transfer: Atletico Madrid to Man United, June 2011

Signed to replace Edwin Van der Sar, De Gea initially struggled to cope with the physicality of the Premier League.

He turned it around, though, and soon emerged into one of the world's best goalkeepers.

Rating: 9/10

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Click here to view: Rating Sir Alex Ferguson's 25 most expensive signings of his career out of 10 (10-1)