The world number 99 said he would do the best he could against Russian Aslan Karatsev in the last eight after his 3-6, 7-6(5), 7-6(8) victory against the American, ranked 10th.

"I'll tell you a secret, we had a practice, I lost 6-0 with Karatsev," said Zhang.

"I'll do my best. Here everyone is a great player, huge player. They all have some very good results. (I will) try to do the best I can do."

In February Wu Yibing beat John Isner in the Dallas Open to become the first Chinese player to lift an ATP tour trophy.

Wu beat Fritz in Dallas on the road to the final, securing a first victory over an ATP top ten opponent for a Chinese player.

Zhang followed suit in the Spanish capital to hit a new milestone in a superb year for Chinese tennis.

"I didn't really think about ranking, because you just need to give the best you can," said Zhang.

"Before the match, you know it's a very tough player. There is no weakness, so (I) just tried what I can do."

Zhang saved three match points in the tie-break, continuing his strong run after upsetting Briton Cameron Norrie, ranked 13th, on Monday.

He had already become the first Chinese player to break into the top 100 of the ATP rankings in October 2022.

He is now guaranteed to climb to at least world number 66 on Monday, the highest ranking of his career.