Stefanos Tsitsipas, the defending champion, came back from a set down in the last set to beat Diego Schwartzman and advance to the Monte Carlo Masters semi-finals, where he will meet Olympic winner Alexander Zverev.

Tsitsipas, the third seed from Greece, was a set and 5-2 up at one point and appeared to be on his way to the final four.

His Argentine opponent, on the other hand, fought back only to be defeated in a quarter-final that ended at 11:00 pm local time.

“I don’t think I’ve ever made such a comeback in my career. It was crazy… I found the resources and I’m proud of it,” said Tsitsipas.

In slightly over three hours, second-seeded Zverev defeated Italian 12th-seed Jannik Sinner 5-7, 6-3, 7-6 (7/5) in the final.

Grigor Dimitrov and Alejandro Davidovich Fokina advanced to the other semi-final.

‘Sad to have won’

“Sad to have won,” said an ironic Zverev to a crowd made up of many vocal Italians.

With a 2-6, 6-4, 6-3 victory, Davidovich Fokina added Indian Wells champion Taylor Fritz to his list of high-profile victims this week.

In the second round, the 22-year-old Spaniard, who is ranked 46th in the world, defeated world number one Novak Djokovic.

On Saturday, he will face Dimitrov, who defeated Hubert Hurkacz of Poland 6-4, 3-6, 7-6 (7/2) in three sets.

“When you beat the world number one it gives you a lot of confidence physically, mentally and technically,” said Davidovich Fokina.

“I am pushing myself every match to play harder and harder.”

Zverev, the world number three, shook off a thigh issue and appeared to have the upper hand in the opening set, reeling off a string of 13 straight points to take a 4-1 lead against a 20-year-old opponent who was suffering from a blistering foot.

Sinner, boosted by a boisterous Italian crowd on the French Riviera not far from home, rallied to 4-4, with a Zverev double fault allowing the Italian to close out the opening set.

Sinner broke for a 2-1 lead in the second set, but Zverev dug deep to go up 5-3 and retain serve for a tiebreaker.

In the third set, the pair traded breaks once more, with Olympic champion Zverev edging a close tie-break on his first match point to reach the semi-finals for the second year in a row.

Fritz not feeling well

Even in the opening set, Fritz struggled as his Spanish opponent heaped on the pressure, with the American complaining of stomach aches twice before obtaining treatment from a doctor on the court.

The 10th-seeded American, who upset Rafael Nadal’s perfect start to the season in Indian Wells in March to win his first Masters title, nonetheless won the first set with a second break of serve.

When Fritz, astonished at the Spaniard retrieving a smash, sent his shot out, Davidovich Fokina battled back and levelled the match with his first set point.

Davidovich Fokina was awarded two match points after a netted smash from Fritz. The first was saved, but the Spaniard made no mistake with the second, blasting a brilliant right-handed winner.

Dimitrov won a thrilling fourth set tie-break to reach the Monte Carlo final four for the second year in a row.

The Bulgarian retained his lead in the first set, breaking 4-2 with consecutive drop shots that caught his 29th-ranked opponent off guard. Hurkacz, rated 11th, did the same in the second, breaking 4-2 with consecutive drop shots that caught his 29th-ranked opponent off guard.

The Pole broke twice in a tense third set and was serving for the match at 5-4, but the former world number three battled his way back, dominating in two hours and 27 minutes to advance to his third Masters final.