The manager noted the decision regarding the Bournemouth player was a close call, providing him an immediate opportunity to integrate further with the senior national setup.
"That showed me his character and I'm delighted he'll be with us because that was a close call and he gets a chance to get a step closer and a cap," Tuchel added.
Tuchel faces domestic pressure over his squad selection, with former Premier League forward Troy Deeney criticizing the exclusion of creative players like Phil Foden and Cole Palmer.
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The preparation players will join the main roster for two friendly matches in Florida, starting against New Zealand at Raymond James Stadium in Tampa on June 6, followed by a game against Costa Rica in Orlando on June 10.
