Carlos Alcaraz believes he still has a way to go to reach top form after moving into the semi-finals of the Japan Open on Sunday.

The Spanish world No. 2’s latest win was over Denis Shapovalov, who was forced to retire when down 7-6(3), 2-1 due to injury. Shapovalov appeared to hurt his hip at the start of the second set and took a medical timeout before calling it quits.

During the match, Alcaraz faced a stern test in the first set, where he was broken three times and had to save a set point down 4-5. He was also down a mini-break at the start of the tiebreak before going on to win seven of their next eight points.

“It was a little bit frustrating with my serve,” Alcaraz said afterwards.

“I couldn’t find a good way of serving, struggling almost every game on serve but I’m happy the way that I came back after every break.

“It’s a shame that he had to pull out and going through to a semi-final like this, it’s not the way that I want it but sometimes in sport it’s tough and you’re gonna accept it.”

Tokyo is just the third event Alcaraz has played since returning from a wrist injury that sidelined him for five months. Earlier this month, he reached the quarter-finals of the US Open before losing to Ben Shelton. Then at the Laver Cup, he won one singles and one doubles match during the three-day event.

Despite a relatively solid return to the Tour, Alcaraz sees plenty of room for improvement in his game.

“I think it’s far from what I want it to be,” he said of his current form.

“I’m doing great things off the court. I’m practising well. I’m trying to do everything when I’m playing the matches because it’s different in competition than in practise, you gotta find a way.”

“Hopefully, the tournament ahead and the matches ahead are gonna be a great test for me.”

Alcaraz will play qualifier Jaume Munar in the next round, who defeated Kyrian Jacquet 6-4, 6-2 in his latest match. Munar also knocked Taylor Fritz out of the tournament earlier this week.

In the other section of the draw, Jiri Lehecka will take on Valentin Vacherot in Monday’s semi-finals.