Bayern Munich's Carlo Ancelotti insists he has the full support of his club, amid doubts over the Italian's future.
Having joined BVB on a three-year deal in summer 2015, Tuchel and the club put back talks about a new deal until the summer.
Pulisic, 18, made his first team debut in February 2016, and the United States winger is set for his 40th competitive appearance of this season.
The Spain international, 26, is in his fourth year at the club and his existing deal had been due to expire in the summer of 2019.
Bayern lost to Real Madrid in the Champions League quarterfinals last week and crashed out of the DFB Pokal to Borussia Dortmund in the semifinals.