Joao Felix will wear the number 11 shirt at Chelsea after he completed a six-month loan deal from Atletico Madrid.
The Portugal international wore the same number at the La Liga club.
The Blues will pay a £9 million loan fee for Felix, who fell out with Atletico manager Diego Simeone.
There is no option to buy included in the loan deal and Felix has also signed a one-year extension with Madrid.
This means he will likely return to Spain when his spell at Stamford Bridge ends.
The forward has registered four goals and three assists from his 14 La Liga appearances.