Boss Jose Mourinho says winger Victor Moses brings strength, pace and aggressiveness into the Chelsea squad.
The 24-year-old was one of the most dangerous players in a surprise 4-2 defeat against New York Red Bulls and is expected to stay at Stamford Bridge amid interest from former club Stoke City.
"I see him fitting in. he's strong, he's experienced and he knows the Premier League well," Mourinho said after the game.
"He's fast and aggressive.
"Okay, he has to learn how to play with us but I'm happy with his week and his 45 minutes. Let's see what happens but Victor had an evolution in the last couple of years."
Asked about Asmir Begovic's nightmare debut, Mourinho said: "He was very tired, the same as Courtois.
"When the goalkeepers are very tired the coordination is low, the agility doesn't exist, and the speed of reaction doesn't exist. Courtois made a mistake in the first half with the ball at his feet.
"Begovic in the second half was not sharp in his reactions but it's a consequence of being tired from training.
"I'm so happy to have him and in the next game against PSG he will start. He will play the first half. There's no problem, it's just a process."