Second seed Daniil Medvedev battled oppressive heat and humidity that required him to take two medical timeouts on his way to beating Fabio Fognini of Italy to reach the quarterfinals of the 2020 Olympics on Wednesday in Tokyo.

The heat index hit 99 degrees as the Russian fought off Fognini 6-2,3-6, 6-2. Before the third set, the 25-year-old Medvedev cooled off in the shower before returning to the court to finish off the match in two hours, 26 minutes. In the quarterfinals, Medvedev will meet the sixth seed, Pablo Carreno Busta of Spain, who defeated German Dominik Koepfer 7-6 (7), 6-3.

Stefanos Tsitsipas of Greece couldn't shake a leg injury, and the third seed was upset by Ugo Humbert of France 2-6, 7-6 (4), 6-2. Humbert will meet Russian Karen Khachanov, who eliminated Diego Schwartzman of Argentina 6-1, 2-6, 6-1.

The conditions didn't seem to affect top seed Novak Djokovic, who cruised past Alejandro Davidovich Fokina of Spain 6-3, 6-1 as the Serb continues in the fourth leg of his quest for the Golden Slam --- an Olympic gold medal and all four Grand Slam tournaments of the year. If he wins gold and the U.S. Open in September, he will join Steffi Graf of Germany (1988) as the only player to reach those heights.

Standing in his way in the quarterfinals is Kei Nishikori of Japan, the former world No. 4, who fought off Ilya Ivashka of Belarus in the first set but blew past him in the second with a 7-6 (7), 6-0 win.

The final quarterfinal will feature fourth-seeded Alexander Zverev of Germany, a straight-sets winner over Georgian Nikoloz Basilashvili, against Jeremy Chardy, who ousted Liam Broady of Great Britain.

Generali Open

Top-seeded Casper Ruud of Norway was pushed the limit by a lucky loser from qualifying before advancing to the quarterfinals in Kitzbuhel, Austria.

Ruud outlasted Spain's Mario Vilella Martinez 7-5, 5-7, 6-4 in a match that lasted almost 2 1/2 hours. Ruud faced just two break points in the match, and he lost both, while he converted three of his seven break opportunities.

Second-seeded Roberto Bautista Agut played a similarly tight match but wound up losing 6-4, 6-7 (5), 7-5 to Spanish countryman Pedro Martinez. Another Spaniard, fourth-seeded Albert Ramos-Vinolas, lost 7-6 (3), 1-6, 7-5 to Italy's Gianluca Mager.

Also reaching the quarterfinals were third-seeded Filip Krajinovic of Serbia, Daniel Altmaier of Germany, Jozef Kovalik of Slovakia, Arthur Rinderknech of France and Mikael Ymer of Sweden.

Truist Atlanta Open

U.S. teen Brandon Nakashima stunned top-seeded Milos Raonic of Canada in the second round at Atlanta, rallying for a 5-7, 6-3, 7-6 (4) win.

Nakashima, a 19-year-old ranked 115th in the world, reached his first career ATP Tour final last week, falling in the title match at Los Cabos, Mexico, to Great Britain's Cameron Norrie.

Fifth-seeded Taylor Fritz also moved on to the Atlanta quarterfinals, defeating fellow American Steve Johnson 6-7 (5), 6-4, 6-1. Australia's Jordan Thompson beat German qualifier Peter Gojowczyk 7-6 (6), 6-4.

The last match of the night was another all-U.S. affair, with fourth-seeded Reilly Opelka taking on qualifier Bjorn Fratangelo.