Daniil Medvedev has criticized the balls used at the ATP China Open after an "up and down" match against Ugo Humbert in the quarter-final at the National Tennis Center in Beijing.

The second seed ousted Tommy Paul and Alex de Minaur in straight sets to set up the clash with the World No. 36. However, he had more difficulty against the Frenchman, having to fight back after he lost the second set. Ultimately, he won the match in three sets 6-4, 3-6, 6-1 but made his frustrations clear afterwards.

The 27-year-old has previously criticized the balls being used at the ATP 500 tournament, saying that they are much fluffier than usual and likening them to a grapefruit after his match against de Minaur.

"As soon as you play some shots with them, they go very big, much [fluffier]… it becomes like a grapefruit. We’re basically playing 30-shot rallies because it’s almost impossible to hit a winner.

"With these balls, you have to be 100 per cent on every point, until the last point of the match. I managed to do it well so this, I’m happy about," Medvedev told AFP news ahead of his clash with Humbert.

After securing his place in the semi-final, the Russian continued his criticism of the balls, suggesting that the problem was not isolated to this specific tournament.

"All the match was pretty up and down... These balls on hardcourts are a joke. 3rd set I lose my serve and I win 6-1. It’s not normal. But we’ve played like this all year. So okay," he said.

However, top seed Carlos Alcaraz has been more relaxed about the balls at the tournament, saying that it was just something that the players had to get used to.

"I felt it since the first practice that I did here in Beijing. It is something tough but the tennis player has to get used to that. They change balls in every tournament or almost in every tournament is a different ball. You have to get used to that.

"It’s kind of different feeling when you are coming into a tournament, is like: What is going to be the ball? It’s a question that I think every player is asking themself about the balls. Here in just one game, two games, the ball becomes different from the new ones. It’s kind of different play, and you have to get used to that," he said.