Novak Djokovic of Serbia hits a return during the men's singles quarterfinal match between Novak Djokovic of Serbia and Lorenzo Musetti of Italy at the Australian Open tennis tournament in Melbourne, Australia, Jan. 28, 2026. (Photo by Hu Jingchen/Xinhua)

MELBOURNE, Jan. 28 (Xinhua) -- World number four Novak Djokovic advanced to the Australian Open semifinals on Wednesday after fifth seed Lorenzo Musetti retired with a right groin injury despite leading by two sets.

Musetti was on course for the biggest win of his career after taking the opening sets 6-4, 6-3 against a below-par Djokovic. However, he suffered the injury early in the third set, struggled with his movement and retired while trailing 3-1.

Djokovic had taken a medical timeout after the second set, with his right foot strapped due to a blister.

"I feel really sorry for him. He was a far better player, I was on my way home," Djokovic said. "These things happen in sport. It's so unfortunate. He should have been a winner today."

Djokovic entered the quarterfinal after receiving a walkover in the fourth round when 16th seed Jakub Mensik withdrew with injury.

The 38-year-old will next face either two-time defending champion Jannik Sinner or eighth seed Ben Shelton. ■

Novak Djokovic of Serbia hits a return during the men's singles quarterfinal match between Novak Djokovic of Serbia and Lorenzo Musetti of Italy at the Australian Open tennis tournament in Melbourne, Australia, Jan. 28, 2026. (Photo by Hu Jingchen/Xinhua)

Novak Djokovic (R) of Serbia greets with Lorenzo Musetti of Italy during the men's singles quarterfinal match between Novak Djokovic of Serbia and Lorenzo Musetti of Italy at the Australian Open tennis tournament in Melbourne, Australia, Jan. 28, 2026. (Photo by Hu Jingchen/Xinhua)

Novak Djokovic of Serbia reacts during the men's singles quarterfinal match between Novak Djokovic of Serbia and Lorenzo Musetti of Italy at the Australian Open tennis tournament in Melbourne, Australia, Jan. 28, 2026. (Xinhua/Ma Ping)

Novak Djokovic of Serbia reacts during the men's singles quarterfinal match between Novak Djokovic of Serbia and Lorenzo Musetti of Italy at the Australian Open tennis tournament in Melbourne, Australia, Jan. 28, 2026. (Xinhua/Ma Ping)

Novak Djokovic of Serbia greets the audience during the men's singles quarterfinal match between Novak Djokovic of Serbia and Lorenzo Musetti of Italy at the Australian Open tennis tournament in Melbourne, Australia, Jan. 28, 2026. (Xinhua/Ma Ping)

Lorenzo Musetti of Italy reacts during the men's singles quarterfinal match between Novak Djokovic of Serbia and Lorenzo Musetti of Italy at the Australian Open tennis tournament in Melbourne, Australia, Jan. 28, 2026. (Xinhua/Ma Ping)

Lorenzo Musetti of Italy hits a return during the men's singles quarterfinal match between Novak Djokovic of Serbia and Lorenzo Musetti of Italy at the Australian Open tennis tournament in Melbourne, Australia, Jan. 28, 2026. (Xinhua/Ma Ping)

Lorenzo Musetti of Italy hits a return during the men's singles quarterfinal match between Novak Djokovic of Serbia and Lorenzo Musetti of Italy at the Australian Open tennis tournament in Melbourne, Australia, Jan. 28, 2026. (Photo by Hu Jingchen/Xinhua)

Lorenzo Musetti (C) of Italy receives medical treatment during the men's singles quarterfinal match between Novak Djokovic of Serbia and Lorenzo Musetti of Italy at the Australian Open tennis tournament in Melbourne, Australia, Jan. 28, 2026. (Photo by Hu Jingchen/Xinhua)

Lorenzo Musetti of Italy reacts during the men's singles quarterfinal match between Novak Djokovic of Serbia and Lorenzo Musetti of Italy at the Australian Open tennis tournament in Melbourne, Australia, Jan. 28, 2026. (Photo by Hu Jingchen/Xinhua)