Chelsea have signed Olivier Giroud from their London rivals Arsenal with the French striker signing an 18-month contract with the Premier League champions.
The 31-year-old's arrival at Stamford Bridge has allowed Michy Batshuayi to leave on loan for Borussia Dortmund for the rest of the season.
Giroud says he's joined "one of the biggest teams in the Premier League".
"They have won maybe the most trophies in the last six or seven years. It’s a massive club and I am proud to sign for Chelsea, and I’m looking forward to playing."
Despite not regularly holding down a starting place at the Emirates in his six seasons at the Gunners, Giroud scored 105 goals in 253 appearances.
Chelsea director Marina Granovskaia has described the forward as "a proven talent at the top level".
"He has scored goals regularly throughout his career and is well accustomed to English football and the Premier League. We are sure he will be a fantastic signing."
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Chelsea had been linked with Andy Carroll, Peter Crouch and Ashley Barnes in this window and Giroud's arrival has allowed Michy Batshuayi to leave on loan for Borussia Dortmund for the rest of the season.
Batshuayi will help fill the void left by Pierre-Emerick Aubameyang's club record move to Arsenal.
He's moved in a bid to secure a place in Belgium's squad for this summer's World Cup.
"In order to achieve my big goal, I want to play as much as possible and score many goals. The World Cup takes place in the summer."