World No. 49 Daniil Medvedev recorded the biggest upset in the first round of Wimbledon Monday after beating world No. 3 and fifth seed Stan Wawrinka, 6-4, 3-6, 6-4, 6-1, for his first Grand Slam win. The 21-year-old Medvedev, who turned pro in 2014, was winless in two previous Grand Slam outings -- at the 2017 Australian Open and the French Open earlier this year – but he stunned the world by beating Wawrinka in two hours and 13 minutes.

Wawrinka disappointment

It was a painful defeat for Wawrinka, who was expected to go deep into the tournament.

He even brought in Paul Annacone, the former coach of Roger Federer and Pete Sampras, to help his grass game. However, a left knee injury hampered his game starting in the second set, allowing Medvedev to clinch the victory.

Wawrinka’s loss came after 20th seed Nick Kyrgios retired from his first-round match against Pierre-Hugues Herbert due to a left hip injury that he sustained two weeks ago at the Aegon Championships. Herbert will next face Benoit Paire, who defeated Rogerio Dutra Silva in four sets.

Nadal clinches 850th career match win

Meanwhile, world No. 2 Rafael Nadal clinched his 850th career match win after beating John Millman, 6-1, 6-3, 6-2, in his opening round match. Nadal became the seventh player to reach the plateau behind Jimmy Connors, Roger Federer, Ivan Lendl, Guillermo Vilas, John McEnroe and Andre Agassi.

If Nadal reaches his sixth Wimbledon final, he will snatch the world No. 1 ranking from Andy Murray for the first time since June 2014. Nadal will have face Donald Young as his next assignment. Young advanced after Denis Istomin retired after two hours and 12 minutes while trailing (5-7, 6-4, 6-4, 4-2).

Kei Nishikori, Tsonga reach second round

Ninth seed Kei Nishikori started his campaign with an impressive straight-set victory over Italian Marco Cecchinato in just 72 minutes. Nishikori, who hit 35 winners, will next face Sergiy Stakhovsky, who defeated Julien Benneteau in four sets.

No. 12 seed Jo-Wilfried Tsonga was equally impressive in his opening match, needing just 88 minutes to beat wild card Cameron Norrie in three sets.

In the second round, Tsonga will collide with Simone Bolelli, who ousted Yen-Hsun Lu in four sets. Seventh seed Marin Cilic also advanced after beating Philipp Kohlschreiber in three sets in one hour and 56 minutes. Cilic hit 47 winners, including 15 aces, as he broke a two-game losing streak against Philipp Kohlschreiber.