Fortune was on Andrey Rublev's side at one controversial moment during the third set of his win over Luciano Darderi on Thursday. The pair clashed in the quarter-finals of the Hamburg Open, and it went the distance as Rublev held his nerve to book himself a spot in the semis.

A back-and-forth contest had seen Rublev dominate the first set before Darderi came roaring back to take the second. A contentious point in the third began with Rublev being put on the defensive by Darderi and stretching for a backhand which looked like it was heading for the net before creeping over.

Unfortunately for Darderi, during his approach, the ball kid closest to him was seemingly convinced that Rublev's shot was bound for the net and sprinted off his mark before backtracking.

Darderi flashed a look towards the ball kid before the point had been settled and played a weak forehand to Rublev, who responded with a shot the Italian could not get back within the white lines. Darderi started protesting to chair umpire Richard Haigh even before his final shot had landed beyond the baseline.

But because Haigh did not see the ball kid's movement, and there was no video review available, the point went to Rublev. That put the Russian 4-1 up and firmly en route to a 6-1 3-6 6-3 victory.

Reviewing the incident, Tennis TV commentator Barry Cowan said: "The ball kid has already moved and Darderi looks to his left to see the ball kid moving across. Absolutely, he is well within his rights [to complain]. This is not something after the point where he's trying a fast one, but I don't know whether Richard Haigh saw it."

Rublev has had an up-and-down clay-court season and he will be glad to have found form in Hamburg on the eve of the French Open.

The 27-year-old will face a qualifier or a lucky loser in the first round at Roland-Garros. But he has a Hamburg Open semi-final to contend with in the meantime, and he seems to be feeling comfortable.

After defeating Darderi, he admitted: "Today I was playing with a new racquet. I don't know why. Don't ask me. Sometimes I have no explanation. It felt good."

Rublev will head to Paris as the 17th seed with hopes of bettering the career-best quarter-final runs he managed in 2020 and 2022.