Wow! Black to play
While the white queen can be taken either by the Qb5 or the Rc8, both are fatal, as Black would then have only defender of the e8 rook, and 20.Rxe8+ would lead to mate on the next move. 19.Qc4 also prevents Black tricks based on the weakness of White's back rank. For example, 19.b3?? Qxe2! would have been a killer: do you see why?
So Carlos Torre played the only move that controls the e8 square: 19...Qd7.
White to play
What was White's reply? How deeply can you analyze the continuations?