With the new club season beginning in August, Europe's top teams have been trying to complete their transfer business quickly. 

Some have succeeded. Manchester United have completed the biggest deal of the summer so far. 

They've signed Romelu Lukaku from Everton for £75 million and the striker is already impressing in pre-season. 

Current Premier League holders Chelsea aren't far behind. The Blues have confirmed the transfer of Alvaro Morata from Real Madrid. It's believed his fee could rise to around £70 million.

Add that to the money Roman Abramovich has already spent on Tiemoue Bakayoko and Antonio Rudiger and their spending is well over £100 million already, with more deals expected.

It's clear both these teams are strengthening to take on the challenge of next season's Champions League. Neither side were in the competition last year. 

One of the teams they could come up against in the groups or the knockout stages is Barcelona. The Spanish side are one of Europe's heavyweights and always challenge for the title. 

However, unlike United and Chelsea, the Catalan side are yet to add any world-class talent to their squad this summer. 

The biggest move they've made in the off-season is bringing winger Gerard Deulofeu back from Everton, for a fee of just over £10 million.

To make matters worse, there's been huge speculation surrounding the future of their Brazilian forward Neymar.

The 25-year-old has been linked with a move to Paris Saint-Germain, who are apparently willing to pay an incredible €222 million to secure his signature.  

Perhaps preparing for the worst, it was revealed that Barcelona made a formal approach for Liverpool's Philippe Coutinho a few days ago, bidding £72 million.  

The Red's swiftly rejected, with Jurgen Klopp adamant that Neymar's international teammate will stay in England.    

However, Barca are ready to make an improved bid and it will surely test Liverpool's resolve.

Reports from the Mirror suggest that Ernesto Valverde's side will go as high as £80 million to tempt the English club to part with their best player.

That is a huge amount of money that could be invested into other players. 

But with Klopp struggling to get RB Leipzig to part with Naby Keita, his number one target, he will be reluctant to sell Coutinho, who is his star man. 

Should Liverpool let Philippe Coutinho go to Barcelona? Have your say in the comments below.