When Kevin-Prince Boateng clattered into Michael Ballack 35 minutes into the 2010 FA Cup final it seemed his ties with Germany had been severed for good.
The Portsmouth midfielder's challenge was cynical and thuggish and marked the beginning of the end of the Germany captain's career.
Ballack missed the 2010 South Africa World Cup and never played for Chelsea again, moving to Bayer Leverkusen and then retiring.
'I've called the coach of the national team and he's naturally disappointed. Now I have to let it sink in.'
Boateng, who represented Germany at U21 level, had recently changed his allegiance to Ghana. His father, Prince, is Ghanaian and his mother is German. His brother, Jerome, is a Germany international. The Ballack incident was the final straw for the German public.
The tackle led to what was described as a 'hate campaign' against Boateng in Germany, and he claimed he had been turned into an 'evil enemy'. 'What is happening has gone too far,' he said.
'Some people have managed to involve my family in this whole affair and we have been turned into an evil enemy.
'On the other hand, many are minimising and ignoring the slap around the face I got from Michael Ballack (earlier in the game).
'Even my public apology a week last Monday has been swept under the table. People have overstepped the mark.'
Germany newspaper Bild branded his tackle a 'nasty revenge foul' and a 'revenge attack', for a long running feud the pair had after Ballack accused him of being arrogant when they both played in the Bundesliga.
Boateng had left Hertha Berlin in 2007 for Tottenham, with the German newspapers describing him as a 'ghetto kid'.
His time in England with Spurs was unfulfilling - spending more time enjoying the footballer's lifestyle than working hard.
It seemed like his talent had been lost amid the trappings of fame and fortune, a flame extinguished under a heap of cash.
He was one of Ghana's best players at the 2010 World Cup and afterwards moved to Genoa in Italy, but instantly was sent to AC Milan on loan.
Boateng helped Milan to the Scudetto in 2011, playing in a multitude of roles - from central midfielder to second striker, as well as on the flank. He became a star.
In April he had told Gazzetta dello Sport: 'If we are to win the Scudetto, I will dance the moonwalk dressed as Michael Jackson, hopefully on the pitch. I have never won anything important in my career. The Scudetto would be a great conquest.'
He did not renege on his promise and his moonwalk at AC Milan's celebration night has gone down in Milan's history.
The Ghanaian was later noted for leading Milan off the pitch in a friendly against Pro Patria in January this year after racist abuse from the stands - and now sits on a FIFA anti-racism taskforce.
Boateng believes players found guilty of racism should not be allowed to play again.
'If there's a fan who has done something wrong and he can never come to the stadium again, that is something that can hurt you because you're a fan and you love the sport,' he said.
'Or a football player who does something wrong, who is racist, and can never play for the club again or can never play in the country again - these are the things that hurt and I think this is the right way to go.'
Another - slightly less commendable but no less interesting - aspect of Boateng's life is the claim from his fiance that 'he is always injured because we have sex seven to 10 times a week'.
Sports Illustrated model Melissa Satta revealed the details back in January 2012 - Boateng had only started 11 Serie A games that term.
But at Milan he developed into a football personality and when he returned to Germany this summer with Schalke, the villain of 2010 had been forgotten.
Bayern Munich's Matthias Sammer, who once labelled him 'unmanageable', now says Boateng has 'developed fantastically, but still kept his identity'
It seems the tensions of the past have eased over time and. Boateng is comfortable playing back in his former home country, that he has been forgiven for his challenge on Ballack.
But whether the visiting Chelsea supporters have forgiven and forgotten is another thing - he is sure to be barracked if fit enough to start.
'If he trains again and tells me he is fit then he's fit,' said Keller.
The Kevin-Prince Boateng we know today will be desperate to play, to answer the jeers on the pitch.
Source: Daily MailÂ