Chelsea have signed Olivier Giroud from Arsenal, with Michy Batshuayi leaving Stamford Bridge to join Borussia Dortmund on loan.
The Blues announced the arrival of France striker Giroud on an 18-month-contract and Batshuayi's departure until the end of the season.
Giroud said on the Chelsea website: "Chelsea is 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."
Giroud has struggled to hold down a regular starting spot since joining Arsenal from Montpellier in 2012, but Chelsea director Marina Granovskaia said: "Olivier is a proven talent at the top level and we are very pleased to call him a Chelsea player.
"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."
Batshuayi arrives in Dortmund as a direct replacement for Pierre-Emerick Aubameyang, who completed his move to Arsenal earlier on Wednesday.
The Belgian is also after regular football to make sure of his place in Belgium's World Cup squad, telling the Dortmund website: "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."