Chelsea boss Thomas Tuchel is delighted with the progress of Christian Pulisic.

Tuchel feels the American is making sure and steady progress, adding that his physical health is so important given the explosive nature of his game.

"Fitness is always important for Christian because he has this huge physical impact in the amount of sprints and intensity that he can give to the team on the highest level," said Tuchel.

"This is one of his biggest strengths, and the other thing is he needs to feel confident and calm mentally, and then he can be a huge weapon for us.

"He scored in the last game against West Brom but unfortunately the overall game and his need to go off the pitch at half-time clouded the goal and the impact he could have had with that goal.

"Then again he was very close to scoring and had a huge impact from the bench [against Porto] so we have to take care about him, that he hopefully will not be reinjured, because I feel him stronger and stronger, and more and more self-confident.

"He could be a decisive factor in the next game with his speed, his ability to dribble and his ability to arrive in the box in dangerous situations from balls from the sides and crosses. He normally has the feeling to arrive and to score so hopefully he can have that impact. It's our job to push him there and to calm his mind that he feels the trust and he feels confident."