Answer
Carlos Moyá won his first match against a top 10 player against Thomas Muster. This happened in 1995, when Moyá was just 19 years old. Muster was ranked number 1 in the world at the time, and Moyá was ranked 30th. Moyá won the match in three sets, 6-3, 6-2, 6-3. This was a major upset, and it helped to launch Moyá's career as a top tennis player.