Zverev said this year’s Australian Open is the first time he has been playing “pain-free” in 12 months.
The 28-year-old tore ligaments in his ankle during his French Open semi-final against Rafael Nadal in 2022 – a career-threatening injury that kept him out of action for six months.
“The last 10 days I felt healthy, and pain-free, which I haven’t felt in a long time. Probably in 12 months,” Zverev said after his win over Tien.
“I feel like I’m happy on the court because I am playing pain-free and a good level.”
Zverev has improved his serve in recent years, adding more consistency after double faults previously plagued his game.
In 2020, when he reached the semi-finals in Melbourne and the final at the US Open, he was averaging 5.9 double faults per match.
He has improved on that figure every year since and, in 2025, his average stood at 1.9.
Zverev will face either world number one Carlos Alcaraz or sixth seed Alex de Minaur, the last Australian left standing in singles, in the semi-finals.
