The Canada wing-back has resisted new contract talks amid interest from Real Madrid. His deal runs to 2025.
Tuchel said, "He is our player. He knows how much we value him.
"For me, the length of the player's contract doesn't change anything. "He is playing regularly and doing so at the highest level.
"I trust in sports management. He is still a very young player, we often forget that. He has room for improvement in every way."