Sarr made his debut in the 1-0 win and Tuchel admits they were shaky at times.
He said, "It helps if we have Toni [Rudiger] or Thiago [Silva] with the experience to stay calm and win decisive challenges to escape the pressure and maybe create counter-attacks but we don't want to talk about guys who aren't here.
"If you don't play, you can't get experience and they did very very good.
"In the last 20 minutes we need to talk on how they can do better - there are always opportunities to improve.
"It was not the cleanest sheet we've ever had but very very important and it was up to Edu [Mendy].
"Trevoh played some good matches so far, it's very impressive, he seems to play without any nerves. He is very reliable and I hope he can continue like this.
"For Malang it was a bit more difficult. He was with us for two weeks and we had a feeling for him."
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