The US Open champion lost his serve in the first game but found momentum after fending off two more breakpoints in the fifth, winning the final four games of the first set in which he fired down six aces.

The Russian ripped through the second set in less than half an hour, dropping one first serve point.

“A crucial moment was when he didn’t convert a double-break point for a double break so I managed to make him serve for the set and it’s not always easy,” said Medvedev.

“I felt sometimes I’m, let’s say, kind of a low intensity guy and try to keep my energy and see what’s going on. I felt like today was not enough in the beginning so I tried to pump myself up.”

The intensity will surely be high in his Masters 1000 quarterfinal. If the Russian can beat his next opponent – either Lloyd Harris or eighth seed Hubert Hurkacz – he will replace Novak Djokovic at the top of the rankings.

Kyrgios exits

Australian wildcard Nick Kyrgios lost to Italian Jannik Sinner 7-6(3), 6-3 after a dispute with the chair umpire.

Kyrgios received a point penalty for bad behaviour in the first-set tiebreak and in between sets angrily and repeatedly asked the chair umpire “What is unsportsmanlike?” before walking to his bench and whacking his racket against the court.

The gesture earned him a game penalty, allowing Sinner to open the second set up a break.

Elsewhere in the day’s action, fourth-ranked German Alexander Zverev overcame a solid defensive effort from Australian qualifier Thanasi Kokkinakis to win 6-4, 6-4 and set up a quarterfinal clash with eighth-ranked Casper Ruud.

The Norwegian, who lost to Zverev in the Paris Masters quarterfinals in November, had earlier sent top British player Cameron Norrie packing 6-3, 6-4 in the Grandstand.

“(Ruud is) somebody that really does not miss much,” said Zverev. “He’s somebody that tries to play aggressive with his forehand as well. Got to take away his strength in a way and we’ll see how it goes tomorrow.”