Gonzalo Higuain has joined Chelsea on loan from Juventus for the remainder of the season, the Premier League club have confirmed.
Chelsea then have the option to extend the loan deal for a season or buy Higuain outright for £31m, according to Juventus.
Higuain spent the first half of the campaign on loan at AC Milan, where he scored eight goals in 22 appearances.
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The 31-year-old striker is reunited with Maurizio Sarri at Stamford Bridge, having worked under the Italian during his spell at Napoli.
"When the opportunity to join Chelsea presented itself, I had to take it," Higuain told Chelsea's website.
"It's a team I've always liked that has a lot of history, a wonderful stadium and they play in the Premier League, a league I've always wanted to play in.
"I now hope I can give back that trust Chelsea have shown me out on the pitch. I can't wait to start and I hope to adapt as soon as possible."
Higuain will not be available for Chelsea's Carabao Cup semi-final second leg against Tottenham on Thursday, live on Sky Sports, as the move was not completed in time.
However, he could make his debut for the Blues when they face Sheffield Wednesday in the fourth round of the FA Cup on Sunday.
Chelsea director Marina Granovskaia expects the Argentina international to thrive under Sarri.
"Gonzalo was our number one target in this transfer window and arrives with a proven record at the highest level," said Granovskaia.
"He has previously worked with Maurizio to great effect and is familiar with how the coach likes to play.
"This was not an easy deal for us to do because of the numerous parties involved, but we are delighted we were able to make it happen and we look forward to seeing the impact Gonzalo will make for us in the second half of the season."
AC Milan moved swiftly to replace Higuain at the San Siro by signing Krzysztof Piatek on a four-and-half-year deal from Genoa.
Higuain's move to Stamford Bridge could also pave the way for Alvaro Morata to join Atletico Madrid on loan.
Sky in Italy understands the Spain international is in talks over a loan deal until the end of the season, with the La Liga side holding an option to buy in the summer.