SHANGHAI, China (AFP) — Shanghai Masters top seed Carlos Alcaraz fought through what he called "one of the toughest matches this year" to make the tournament's Final 16 on Monday, beating Britain's Daniel Evans 7-6 (7/1), 6-4.

The Spaniard is the only one of the tournament's top four seeds left after Stefanos Tsitsipas of Greece crashed out in a late-night match to France's Ugo Humbert 6-4, 3-6, 7-5.

Alcaraz's nearly two-and-a-half-hour match was ferociously physical, with 33rd-ranked Evans giving as good as he got, leading at one point by three games in the first set.

But over the course of prolonged and sometimes scrappy rallies that left spectators gasping and groaning, the world number two gradually assumed control, comprehensively winning the first-set tiebreaker.

"That was probably one of the toughest matches I've played this year," the 20-year-old Alcaraz said after the match.

"I tried to stay all the time there, waiting for my opportunities. I had to stay strong mentally, stay strong physically. I'm really happy with the level that I played."

Alcaraz will next play Bulgarian Grigor Dimitrov, who earlier overcame a torrential downpour and a well-matched opponent in Russian Karen Khachanov to win 7-6 (8/6), 6-4.

Alcaraz, a two-time Grand Slam winner, is the favorite to take the title in the absence of world No. 1 Novak Djokovic and is hoping to use his time in China to close the gap on the Serbian at the top of the ATP rankings.

And his pool of main rivals has shrunk as the competition has progressed.

Second seed and defending champion Daniil Medvedev was upset by 26th-ranked Sebastian Korda on Sunday and third seed Holger Rune was taken out a round earlier.

Greece's Tsitsipas joined them in the early hours of Tuesday, after a match in which the 25-year-old never really seemed to find consistent form.

The world No. 1 six looked rattled after losing the first set but regained his composure to answer back with the second.