Conditions were so tough at the Miami Open that Frances Tiafoe seemed to barely have the energy needed to reach the post-match handshake after bowing out to Daniil Medvedev.
Just two days after surviving cramps in his epic victory over Australian Alexei Popyrin, top seed Medvedev was back on court but this time needed just 90 minutes to dispatch Tiafoe 6-4 6-3 and advance to the quarter-finals.
"I think we were both really tired, but I think we made an amazing show. ... I was really happy with my performance today," Medvedev said.
After some early clouds cleared, bright sunshine starting pounding down with the mid-afternoon temperature and high humidity testing both players.
But Medvedev dominated when it mattered most, hitting 24 winners as he took full advantage of a physically struggling Tiafoe.
"It was definitely a tough match," Medvedev said.
"(There were) a lot of great points, some of them he won, some of them I won... The serve helped me a lot today, especially in the second set."
Medvedev is now 10-1 in sets against Tiafoe in their four head-to-head match-ups on the main tour.
Tiafoe was a quarter-finalist at Miami in 2019 but couldn't repeat that feat.
It was easier going in the night session with second-seeded Stefanos Tsitsipas too good for Lorenzo Sonego 6-2 7-6 (7-2) while fourth-seeded Andry Rublev was untroubled in a routine 6-4 6-4 defeat of Marin Cilic.
However, the biggest boilover came when 20-year-old Sebastian Korda stunned fifth-seeded Diego Schwartzman of Argentina 6-3 4-6 7-5 for the biggest win of his career.
It makes for an interesting Thursday for the Korda family: he'll be in the Miami quarter-finals that day while his sisters, Jessica and Nelly, will be playing in the first round of the first women's golf major of the year, the ANA Inspiration.
Korda, whose father Petr Korda won the 1998 Australian Open and reached No.2 in the world during his stellar career, put on a show to delight the evening crowd.
John Isner wasted a match point during a third-set tiebreaker as seventh-seeded Roberto Bautista Agut of Spain closed out a 6-3 4-6 7-6 (9-7) victory.
Hubert Hurkacz claimed his second Canadian scalp in as many days with the Pole edging past Milos Raonic 4-6 6-3 7-6 (7-4), to follow on from his win over Denis Shapovalov.
Meanwhile, Kazakhstan's Alexander Bublik and Italian teenager Jannik Sinner will meet for a spot in the semi-finals after they both progressed to the last eight of an ATP Masters 1000 event for the first time.