Juventus chief Giuseppe Marotta has admitted Arturo Vidal's knee problems played a role in him staying at the club after being relentlessly chased by Manchester United in the summer.

Vidal was understood to have been one of Louis van Gaal's priority transfer targets during the transfer window.

But, according to the Chilean's national team manager Jorge Sampaoli, United resisted confirming their bid of £47.5m until they had received reassurances over Vidal's long-term fitness, after the 27-year-old underwent surgery on his right knee just weeks before the World Cup.

Questions over Vidal's fitness have remained this season as he has failed to replicate the form that saw him recognised as one of Europe's finest midfielders last term.

And, according to Marotta, those injury problems that helped derailed his move to Old Trafford have persisted.

"The injury influenced his departure, even now he doesn't have the best physical condition," the Juventus chief told the Italian media, Inside Futbol report. "For our part, however, there is the clear desire to keep him because we renewed his contract."

Vidal underwent surgery on his right knee to resolve a meniscus problem in early May, just short of a month before Chile's World Cup campaign began in Brazil.

Sampaoli, who guided his country to the knockout stages where they were narrowly eliminated by the hosts, would later fuel talk of the midfielder's move to Manchester, but admitted Vidal's hurried return saw him perform at "30 or 40%" of the level he operated at last season for Juventus.

The midfielder's future at the Bianconeri once again came under scrutiny earlier in the season after he was photographed on a night out on the eve of a top-of-the-table clash with Roma in October.

Vidal was left out of the squad for the following match against Sassuolo amid reports he had been hit with a €100,000 (£78,485) fine but later denied any rift between him and the club.