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The 29-year-old Russian had to recover from a bout of cramp late in the second set to overcome the American teenager in another dramatic clash between the pair.

It was Medvedev's first win over Tien in three meetings. At the Australian Open, Tien prevailed in a five-set thriller that ended just before 3am, and the pair's Beijing and Shanghai clashes have been dominated by Medvedev's battles with his body.

Medvedev was forced to retire from the deciding set of the pair’s semi-final in Beijing with a similar ailment, but this time the former world No.1 was able to get through and rouse a late charge to victory having lost the second set in a tiebreak.

“I think the toughest part was that we played two times [before], and in my opinion he is an unbelievable player, because he doesn’t have a great serve and serve is so important in tennis," Medvedev said after the win.

"Without the serve, he is 19 years old and 30-something in the world and only going up. In my opinion he is such a good tennis player.

“He feels the game so well. There are so many guys right now that just hit strong with every ball they have, and they have an amazing serve which allows them to stay in the tennis match. He doesn’t have it, and he manages to play so good without it. For me to beat him… I thought I was going to lose. I was cramping again and I’m just super happy to manage to do it.”

The match lasted two hours and 53-minute encounter, Medvedev failed to serve out the first set at 5-4 before prevailing in a tiebreak, and led 3-0 in the second.

But Tien roared back and won the second set in a tiebreak, claiming it with relative ease as Medvedev struggled for mobility because of the cramp in his right leg.

Medvedev, who won here in 2019, looked to be gone at that point with a whole set ahead of him, but found a second wind in the decider.

He broke Tien's serve in the ninth game before serving out to earn his first victory.

Now into his third Masters 1000 quarter-final of the season, having reached the same stage at Indian Wells and Madrid, Medvedev will next face No.7 seed De Minaur, who defeated Nuno Borges 7-5 6-2 to book his spot in the last eight.