Chelsea chairman Todd Boehly has described Pierre-Emerick Aubameyang as an "elite striker" after signing the 33-year-old from Barcelona.
Aubameyang joined Boehly's Blues revolution very late on transfer deadline day.
He has signed a two-year contract at Stamford Bridge, just seven months after moving from London rivals Arsenal to Barca.
Aubameyang did well in his short spell in Spain, scoring 13 goals in 24 games, but he told ChelseaFC.com that he had "unfinished business" in England.
"I'm really happy," Aubameyang said in his first official statement as a Chelsea player.
"It's an honor to be part of this team and I can't wait to start. I have some unfinished business with the Premier League so it's good to be back and really exciting."
In a video posted on social media, Aubameyang added that he was sure that Chelsea will "achieve some big things" while he is at the club.
Boehly added: "Pierre-Emerick is an elite striker with a proven track record in the Premier League and his arrival strengthens our squad, giving us new attacking options.
"We are thrilled to have Pierre-Emerick on board with us in the new era at Chelsea and we're really looking forward to working with him."
Chelsea manager Thomas Tuchel is also likely to be excited to work with Aubameyang.
Tuchel was Aubameyang's manager for two seasons at Borussia Dortmund between 2015 and 2017.
Aubameyang scored 79 goals in 95 games for Dortmund during Tuchel's reign.
The Gabon international scored 68 goals and provided 16 assists in 128 Premier League appearances for Arsenal.
Aubameyang is not available to make his Chelsea debut against West Ham on Saturday due to a broken jaw.