The easier option would have been for the Senegal international to kick it as far as he could, but he missed the control and messed up the Cruyff turn he was attempting.
Tuchel says mistakes like that at the time it happened changes games and the goalkeeper would know this.
He told reporters after the game: “ He knows himself. With these kinds of mistakes, we don’t have to speak a lot.
“It’s a huge mistake at a crucial time in the match. It does not help and he’s the one who is most disappointed.
Big summer signing Raheem Sterling gave away a penalty shortly after Mendy’s error and Leeds took full advantage from the set-piece, with in-form Rodrigo scoring his fourth goal in three games.
Jack Harrison who never stopped running then sealed victory after his out-stretched leg directed the ball past Mendy for his side’s third goal and confirm their first win against the Blues since 2002.
Despite the dominance of Leeds, Tuchel insisted they still had enough to beat the west Yorkshire side.
“We can play on a high level and today we lost track. Everything was going well and I still believe we can win with this team in Leeds. I think it’s more our fault than anybody else’s credit.”