Stach has been a revelation for Leeds since completing a £17 million transfer from Hoffenheim last summer.
A set-piece specialist, midfield dictator and destroyer all rolled into one, the German international has produced five goals and three assists in 30 Premier League appearances.
The 27-year-old has played a crucial role in Daniel Farke's men avoiding the drop, but sadly, his season may have just ended in the worst way possible.
Stach went down under an innocuous challenge once Carlos Baleba's boot caught his knee after jumping for a header. The midfielder initially carried on, but play was then stopped five minutes later as he was stretchered off in excruciating pain with an ankle injury and his foot covered in blood.
Julian Nagelsmann is set to announce his Germany squad on May 21, and Stach was set to be a part of it, but this injury could have dealt a crushing blow to his chances as Leeds wait for a verdict.