Throughout the year, there were upsets that shocked fans and players alike, matches that made the world go "Wait...who won?!" Let's take a look back at the Top 10 biggest upsets of 2019.

2

Tournament: Monte Carlo Masters

Rankings: No. 14 vs. No. 1

Seeds: No. 10 vs. No. 1

Head-to-Head: 0-3

If someone was told that Medvedev, who through the entire 2018 season had only two career wins on clay, would defeat the best player in the world at Monte Carlo, they would laugh.

Yet that's exactly what happened during the quarterfinals (seemingly the best round for upsets if previous entries are any indication) of the Masters tournament. 2019 has been the best year of Medvedev's career, winning both Cincinnati and Shanghai, and his ascent may have started here.

Despite losing three previous encounters with the Serbian, Medvedev buckled down and broke Djokovic five times during the match. After 2 hours and 20 minutes, the Russian had himself his first win over a world No. 1. He may have suffered the Big Three curse, immediately losing in the semifinals, but his season only grew stronger from this moment forward.