Worst move puzzles

Normally, the goal of a puzzle is to find a/the best move(s), or a/the winning/moves. ​ However, this puzzle is for the opposite:

Red to play the only _LOSING_ move.

(There are exactly 21 empty cells. ​ 20 of them are winning moves for Red, and 1 of them is a losing move for Red.)

Here are two more puzzles. Red to play the unique losing move.