And the midfielder has the fragment of chipped bone from his ankle preserved in a glass jar to prove it.

It has been a week of recriminations and blame behind the scenes at Chelsea that culminated in a thinly veiled attack by Mourinho on Ballack and Andrei Shevchenko on Sunday for failing to play through their injuries at a critical stage of the season. The Chelsea manager was understood to be so infuriated by Ballack's decision to have an operation in Munich on 27 April that he wanted the Germany captain sacked.

However, it is understood that the early diagnosis by the Chelsea medical staff missed a crucial fact. A challenge on Ballack from Titus Bramble on 22 April - which put him out of the Newcastle game after 18 minutes - chipped a bone in his ankle. It was only when the problem was later detected by the leading sports injury specialist Hans Müller-Wohlfahrt that it became clear Ballack required immediate surgery to stand any chance of playing again this season.

It would appear that in the week after the game Mourinho was convinced that the original diagnosis was correct and Ballack could play on. When the Chelsea manager was then told that Ballack had undergone surgery and would be out of the crucial Premiership match with Bolton he was furious. The game was drawn and, with Manchester United winning at Everton, the title race turned heavily in favour of Old Trafford.

Absent also from the Champions League defeat to Liverpool last Tuesday and Sunday's draw with Arsenal - which handed the title to United - Ballack was clearly the subject of a Mourinho barb after the match at the Emirates. He said that Chelsea's performance had been a lesson on "why some people have success [at Chelsea] and other people don't have success".

Pushed on the point, Mourinho invited reporters to draw their own conclusions: "It's something you can do on your own - not with my contribution." Commenting pointedly on the difference between players he added: "That's why some players have 20,000 votes for player of the season, some have 20 votes, and some have no votes."

Now it will be up to Ballack to show the diagnosis that he would be fit to play again within five days of the injury at Newcastle was wrong. It is understood that he has the medical evidence to prove it when he returns to the club's training ground today. He has the shard of bone that was removed and X-ray pictures that reveal it was affecting the nerves in his ankle. Ballack will tell his manager that he would never have undergone surgery unless it was necessary.

It is understood that in the aftermath of the injury at Newcastle, the player was told by Chelsea that he would be fit to play against Bolton once the blood around the injury on his ankle had cleared. However, on the Friday, the day before the Bolton match, Ballack was understood to be unable to walk and believed that the pain had worsened.

It was then he went to Munich where Müller-Wolfahrt immediately found the problem, and recommended that only surgery to remove the fragment of bone would enable him to play again this season. Any delay, or a return to England, would simply have added days to Ballack's recovery so the player decided to have the operation on the basis that it would give him a chance to be fit for the FA Cup final on 19 May. At the time, there was still the possibility of Chelsea reaching the Champions League final four days later.

Suggestions that Ballack's ankle injury was the same as Ashley Cole's ankle problem were based on the original diagnosis which did not locate the chipped bone. Ballack is not the delicate, injury-prone player that might have been suggested. In August 2001 he broke a toe and, using painkillers, played on all season for Bayer Leverkusen, eventually reaching the Champions League final.

While Ballack should be confident of patching up his relationship with Mourinho, the future of Shevchenko is less clear. Chelsea confirmed yesterday that his "groin hernia operation" had been brought forward from the end of the season and will take place today, which means the £31m striker will not play against Manchester United in the FA Cup final.

Frank Lampard said after the draw with Arsenal that Chelsea were "men enough to say well done to Manchester United and we'll have to come back like the strong bunch we are".

Lampard said: "We have to iron out a few problems, but that's football, no one wins the League every year. If there are kinks the only way you show the strength of the club is by coming back stronger. That's what United did in the 1990s. That's our aim now."

Mourinho and Benitez take stick for lack of artistry

Jose Mourinho and Rafa Benitez have been accused of suffocating the game by Real Madrid's former director of football, Jorge Valdano. The Argentine World Cup winner, who signed David Beckham from Manchester United, made his attack as he described the Champions League semi-final second leg between Mourinho's Chelsea and Benitez's Liverpool last week.

"Put shit hanging from a stick in the middle of this passionate, crazy stadium and there are people who will tell you it's a work of art," he said. "It's not: it's shit hanging from a stick. Who played well at Anfield? I'm not talking about specialists like Makelele, Mascherano, Essien or Carragher - those whose vocation shines in tough battles.

"Chelsea and Liverpool are the clearest, most exaggerated example of the way football is going: very intense, very collective, very tactical, very physical, and very direct. The control and seriousness with which both teams played neutralised any creative licence, any moments of exquisite skill."

Valdano blamed the managers. "I believe that those who did not have the talent to make it as players do not believe enough in the talent of players. They do not believe in the ability to improvise."

Jack Rashleigh