Veteran John Isner says he will be feeling his age when he faces off on Sunday in the final of the ATP Dallas tournament against a young Chinese record-setter.

The 38-year-old Isner will bid for his 17th career title against Wu Yibing after the 23-year-old upset top seed Taylor Fritz 6-7(3), 7-5, 6-4 to become the first Chinese man to reach an ATP Tour final in the Open Era.

Isner is more worried about how his body will hold up after he piled on 31 aces to defeat compatriot JJ Wolf in their semi-final – along the way he became the first man to win 500 tiebreaks.

“Truthfully, (the body) feels terrible right now,” Isner, who is loath to venture much outside of his home country, said.

“I’m 38 in April. It’s not getting any easier. I started off a little slow, a little sluggish…

“Right now the name of the game is recovery. I’ll get back in the training room and try to get this big body ready for tomorrow.” 

Former No. 1 junior Wu advanced to his breakthrough final with 34 winners against Fritz. 

“I wasn’t thinking about the score or winning or losing. I’m just trying to perform my best,” the No. 97 said.