Jannik Sinner explained he was combatting dizziness and illness as he fell to an epic five-set defeat against Daniil Medvedev in the Wimbledon quarter-finals.

Top seed Sinner, who was forced to take a medical timeout midway through the third set, rallied brilliantly from that issue in the fourth to force a decider in a four-hour tussle on Centre Court.

However, the Italian ran out of steam in the fifth set, with Medvedev going on to clinch a 6-7 (7-9) 6-4 7-6 (7-4) 2-6 6-3 victory.

"Already in the morning I didn't feel great and had some problems," Sinner said after the match when he was asked about his struggles.

"Then with the fatigue, it was tough. 

"I went off the court actually. I didn't want to go off. The physio told me better to take some time because he watched me, and I didn't seem in shape to play. I was struggling physically.

"It was not an easy moment. I tried to fight with what I had.

"I was not feeling great. I didn't vomit. But took some time because I was dizzy quite a lot. Yeah, actually off court I had a little bit the toughest time maybe.

"I retired a lot two years ago. I don't want to retire if it's only a little bit of illness or sick or whatever."

Sinner stressed he did not want to detract from Medvedev’s victory and had been determined to see the match through to the end.

"Nothing to take away from Daniil – he played very smart, good tennis," added the Italian.

"I was still in shape to play somehow. The fifth set I felt a little bit better again. The energy level was a bit up.

"But the energy level was not consistent. It was up and down. Like this, it's also not easy to handle the situations on the court.

"It happens. I was never thinking about retiring. You don't want to retire in a quarter-final of a grand slam."

Sinner has made the last eight or better at each of the last three Wimbledon appearances, but is yet to reach the final.

Medvedev, meanwhile, will take on defending champion Carlos Alcaraz in the semis on Friday, having now matched his best career run at the All England Club.