Aside from the French Open, Muster never reached the final of which Grand Slam?
US Open
Wimbledon
Australian Open
He reached all finals
Answer
The US Open is the Grand Slam tournament that Muster never reached the final of. Muster's best performance at the US Open was reaching the semi-finals in 1995 and 1997.
Mastering Muster: Testing Your Knowledge on Austrian Tennis Pro, Thomas Muster