Willian made his debut in the 2-1 defeat by Basel in the Champions League.
He told “Globe Esporte”: “It’s good to make your debut but it would be even better if it was a winning one.
“Now we have to raise our heads and try to win the next game. I know that I have to try and get better.
“I can’t stop, I always have to try and keep a good pace and that’s what I’ll do.”
Willian added: “I have to show every game, every training session, and then Mourinho will be able to believe in me.”
