It's been day of full of twists and turns at Roland Garros. Day 2 has featured a number of early upsets, with unseeded players showing they are motivated to win, no matter who stands across the net.
1. Pierre-Hugues Herbert d.  Daniil Medvedev, 4-6, 4-6, 6-3, 6-2, 7-5
At the start of the clay-court season, Medvedev asserted himself as a viable threat. The Russian upset Novak Djokovic to reach the Monte Carlo semifinals and advanced to the final in Barcelona a week later. It all came crashing down after that.
Entering Paris with three consecutive losses, Medvedev appeared to be back on track in taking a two-set lead. His first-round opponent, however, did not go away quietly. Despite serving from behind in the fifth set and missing an overhead to break for a 5-4 lead, Herbert made full use of his home support to continue pressing, ultimately outlasting Medvedev.
Ironically, Herbert followed in the footsteps of Nicolas Mahut, who put his doubles partnership with Herber on hold with earlier this season to prioritize singles. On Sunday, it was Mahut who rallied to win from two sets down, knocking out 2018 semifinalist Marco Cecchinato.
2. Veronika Kudermetova d.  Caroline Wozniacki, 0-6, 6-3, 6-3
It's been a disappointing clay-court season for Wozniacki, who retired in Rome and Madrid with two different injuries. The 13th seed started off as strong as one can, handing Kudermetova a bagel in the first.
Kudermetova revealed a much-higher level in the second set, remaining consistent but playing with added aggression. The Dane suddenly began to unravel, and Kudermetova grabbed and held onto the momentum for the three-set comeback.
This marks the Russian's first Top 20 win and also her first time into the second round at a Grand Slam. The 22-year-old certainly will not fly under the radar in her upcoming match.
3. Juan Ignacio Londero d.  Nikoloz Basilashvili, 6-4, 6-1, 6-3
The Argentine pulled off the significant upset of the day on the men's side on Monday when he eased by Basilashvili. The Georgian entered Paris playing well, reaching the semifinal in Lyon before falling to Felix Auger-Aliassime. Londero was making his Grand Slam debut, but you never would have known it given his ease of victory. Next up for Londreo will be crowd favorite Richard Gasquet.
4. Kaia Kanepi d.  Julia Georges, 7-5, 6-1
Kanepi is no stranger to winning, which she reminded everyone with her upset of Georges. The Estonian has been to six Grand Slam quarterfinals at three different Grand Slams.
Georges didn't have great success on clay leading into the French Open, having lost to 29th-ranked Mihaela Buzarnescu in the second round of Rome and, beforehand, falling to Viktoria Kuzmova in the first round of Madrid.
Kanepi will battle Shuai Zhang for a spot in the third round.
5. Filip Krajinovic d.  Frances Tiafoe, 6-2, 4-6, 6-3, 3-6, 6-0
Tiafoe didn't give the win to his opponent Krajinovic without a fight. After throwing up twice on the court, Tiafoe was "very depleted'' for the fifth set. The ill American said he felt fine before the match:
"Throwing up during the match isn't something that normally happens to me," said Tiafoe. "I threw up again when I went to the locker room after the third set. The fifth-set result obviously came to that because (I) was obviously very depleted and had nothing really in me. It was tough to end like that."
Krajinovic has been playing excellent tennis of late. Beginning in April, he reached the Sophia Antipolis Challenger final, advanced to the ATP final in Budapest, and he won the Heilbronn Challenger just over a week ago. With so many clay-court matches under his belt, the Serbian was well-prepared for a lengthy battle.