Roger Federer and Novak Djokovic went from perfectly unbeatable to unbelievably beaten in the quarter-finals of the Shanghai Masters.

Federer and Djokovic had been a combined 13-0 in Shanghai with a spot in the semi-finals on the line, but both lost Friday.

Federer saved five match points in the second set but still couldn’t stop fifth-seeded Alexander Zverev from winning 6-3 6-7 (9-7) 6-3.

Djokovic, the defending champion, lost to sixth-seeded Stefanos Tsitsipas 3-6 7-5 6-3.

“He deserved the victory,” Djokovic said of the 21-year-old Tsitsipas.

“He was the better player in the second and third sets. I started well in the first set, but I wasn’t sharp enough.”

Djokovic had been 8-0 in quarter-final matches at the Shanghai Masters, and won four titles. Federer had been 5-0.

Federer received a code violation for hitting a ball into the stands, and then received a point penalty for unsportsmanlike conduct after flicking a ball into the air when trailing 3-0 in the third set.

The 22-year-old Zverev now leads Federer 4-3 in career meetings.

Until Friday’s match, Djokovic had won 24 straight sets in Asia, a run that included last year’s Shanghai Masters and the title in Tokyo last week.

Tsitsipas has now beaten Djokovic twice in three matches.

The Greek player defeated Djokovic in their first meeting at the 2018 Toronto tournament and Djokovic won their match in Madrid this season.

“It’s the best comeback that I have ever had probably,” Tsitsipas said of Friday’s victory.

Tsitsipas also earned a place at the year-end ATP Finals for the first time on Friday.

But that was guaranteed when third-seeded Daniil Medvedev beat Fabio Fognini 6-3 7-6 (7-4) in another quarter-final match.

Medvedev, who will face Tsitsipas in Saturday’s semi-finals, is one match away from reaching a sixth consecutive tournament final.

He reached his first grand slam final at the US Open, and then won titles in Cincinnati and St Petersburg.