Manchester United goalkeeper David de Gea is in action during their 1-1 Premier League draw against Arsenal in Manchester, England on May 17. Photo: IC

It's a week since the Champions League and the rebuilding process for the two best clubs in Europe has already started in earnest. Winners Barcelona have been quick to deal with the important matter of securing manager Luis Enrique's services for next season and beyond, along with agreeing a new two-year deal with Brazilian fullback Dani Alves. Despite a ban preventing them from fielding new signings until January 2016, the Catalans have also moved quickly to sign Sevilla's Aleix Vidal as competition for the veteran Brazilian.

More worryingly for those hoping to prise next season's trophy away from Barcelona's grasp, the president of the Champions League winners, Jose ­Maria Bartomeu, has said that the club are "­closely monitoring" the France and Juventus midfielder Paul Pogba.

The Turin giants appear to have begun planning for a life without the 22-year-old former Manchester United player. Juventus have won the race to sign free agent Sami Khedira after the German midfielder allowed his contract to run down at Real Madrid. The World Cup winner is the second player that the Old Lady has added to her ranks having previously agreed a 32 million euro ($36 million) deal for Palermo's star striker Paolo Dybala.

Such is the incestuous nature of top-­level European football, it could well be that the Argentinian forward replaces his compatriot Carlos Tevez. The Juventus forward is in talks with last season's Champions League finalists Atletico Madrid, according to their manager, Diego Simeone, but he is also being linked with French champions Paris Saint-Germain.

Barcelona will go into next season's Champions League as favorites, with or without the addition of Pogba. This ­summer is the time for other clubs to try to build a squad that can reach the level of the Spanish treble winners and they are wasting no time in doing so.

Major movement

Pogba might be on the radar of the Camp Nou giants but he is also on the wish list of every major club in Europe. Manchester City have been linked with the Frenchman, as have Real Madrid. It seems likely that he will leave Italy if the transfer fee approaches the 100 million euro record that the Spanish side gave Tottenham Hotspur for Gareth Bale.

Real, the team most angered by Barcelona's historic second treble, especially as they had high hopes of successfully defending their 10th Champions League crown, are well into their own rebuilding process. The club sacked manager Carlo Ancelotti for failing to secure any silverware in his second season and enticed Rafa Benitez from Napoli as his replacement. The former Liverpool manager is set to spend this summer and his first order of business looks set to be a goalkeeper to replace Iker Casillas.

The football world seems in agreement that the man to fill those gloves will be Manchester United's David de Gea. The Old Trafford shot stopper is unlikely to resist a return to his hometown and United fans are resigned to losing him. That move, if it happens, will kick off a flurry of transfers among the Champions League hopefuls, starting at the 20-time champions of England. Louis van Gaal will certainly need a new goalkeeper to rival current No.2 Victor Valdes but that won't be their only spending of the summer as the Dutchman is allowed to invest some of the funds of their huge kit deal with adidas.

United are known to be keen on four of Real's players, including Gareth Bale and Cristiano Ronaldo, and have mooted a swap deal involving Karim Benzema or ­Raphael Varane for their outgoing custodian. United already confirmed the signing of Memphis Depay from PSV Eindhoven before the Premier League season ended, while Radamel Falcao has left the club in Van Gaal's quest to build a new-look United capable of winning him a trophy.

Financial constraints

Despite falling foul of UEFA's Financial Fair Play restrictions, Manchester City and Paris Saint-Germain will be among the biggest spenders, and Chelsea will not be far behind them. The Paris club have been linked with a move to end Angel di Maria's unspectacular stay in Manchester while City have been mentioned as moving for Wolfsburg's Bundesliga MVP Kevin de Bruyne and Liverpool's Raheem Sterling among others.

Transfer fees have risen sharply since the turn of the millennium and this summer will see the trend continue. The transfer record was last broken when Real Madrid signed Bale in 2013 but last summer saw the third, fourth and fifth biggest moves of all time with the transfers of Luis Suarez, James Rodriguez and Di Maria.

Tabloid speculation on who is going where is always to be taken with a pinch of salt but this summer will no doubt break the record for total spending yet again. The bottom line for clubs involved in the Champions League is winning it and this season Barcelona proved that they all have some way to go to do so.