Liverpool left-back Buchtmann, 17, has penned an 18-month deal and concludes the London club's mid-season activity.
Last season, Barcelona dominated its two games against the London club, creating chances left and right.
The value of the three-year, multi-million-pound deal has not been revealed by the east London club.
He has scored nine goals in the two seasons he has been at the west London club.
In the Premier League, the West London club has won just twice in its last 10 games.
WSJ: Andre Villas-Boas: The Collapse of a Coaching Wunderkind
He has since been rejected by another London club Fulham, where he was on trial last week.
Di Matteo has since been appointed Chelsea's permanent boss, while Villas-Boas has swapped one London club for another.
The 63-year-old spent 48 years with the London club before his retirement at the end of last season.
Chelsea had been leading the chase for Robinho, who had insisted he wanted to play for the London club.
But the London club claim the deal foundered because of "Premier League rules".
BBC: SPORT | Football | My Club | Tottenham Hotspur | Spurs confident of Robinson deal
But he admitted he is in need of a new challenge after nine years with the north London club.
The atmosphere inside reminded me of an Oxbridge College or a London Club.
And the result left West Ham level with 18th-placed Hull, who have played one match fewer than the London club.
Hitzlsperger, nicknamed Der Hammer, fired in a left-foot drive to give the London club the lead in the 23rd minute.
Known as "The Invincibles, " the London club is the only team to remain unbeaten throughout an entire Premier League campaign.
The north London club, who controversially recruited Gallas on a free transfer from local rivals Arsenal, finished fourth last season.
Palace's celebrations are tinged with uncertainty as the south London club are in administration and facing serious questions about their survival.
Bosnich joined Chelsea in 2001 on a free transfer from Manchester United but made only seven appearances for the London club.
The Czech keeper has already made more appearances than any other foreign player in the London club's history, representing Chelsea 369 times.
He scored 39 goals in 123 appearances over three seasons for the west London club, while Terry was coming through the youth system.
The London club - backed by F1 multi-millionaires Bernie Ecclestone and Flavio Briatore - have targeted a return to the Premier League by 2010.
In Ancelotti's autobiography, which was published two months ago, the Chelsea manager said Wilkins was a key part of the London club's recent success.
BBC: Chelsea part company with assistant manager Ray Wilkins
Grantham Mayo owns London Club debt, which was restructured in 1993. (The London Club and the Paris Club often clash when countries try to restructure their debts).
United beat Arsenal 3-1 in the second leg and 4-1 on aggregate as the Champions League trophy again eluded Wenger and the London club.
LONDON Jose Mourinho's return to Chelsea became official on Monday when he was hired as the London club's new manager, six years after his acrimonious departure.
The former England centre-half looked ecstatic, celebrating two goals in successive Champions League matches for the London club that spanned three and a half years.
However Briatore, who is also co-owner of the West London club, did not explain what the difference was between a sacking and a contract termination.
He helped the London club win the domestic championship in 2009-10.
The 24-year-old Swiss defender has been limited to Carling Cup appearances this season and has made it clear he wants to leave the north London club.
But the London club faded badly after the break and Everton substitute Jermaine Beckford equalised with a header four minutes before the end of normal time.
应用推荐