“I am feeling unbelievable, to beat Tsonga makes me really happy,” he said.

“I was playing one point at a time, it was not easy conditions and he was playing well too. Hopefully it’s big in Japan, I’m really excited.”

Tsonga admitted: “It was tough, I had a good opponent today. I didn’t play good tennis and I didn’t control everything. It was not a nice moment for me.

“He’s tough to play because he runs a lot and everything comes back.”

Nishikori will meet Andy Murray next. The fourth seed took just 49 minutes to advance after Mikhail Kukushkin was forced to retire through injury after losing the opening two sets.

The Kazakh beat Gael Monfils in five gruelling sets in the previous round and those exertions seemed to hinder him from the start as Murray cruised into a 6-1 6-1 1-0 lead before Kukushkin pulled out with what was later revealed as a left hip flexor problem.

The contest was one-sided from the off, making it difficult to gauge the quality of Murray’s performance but the world number four will be delighted to have got through with the minimum of effort, conserving energy on a hot day.

Kukushkin’s movement was impaired and he struggled particularly on serve, failing to win it during the entire match.

“I played him a few weeks ago (in Brisbane) and it was a tough match,” said Murray. “I expected another one today but it’s so hot.

“I get to conserve a bit of energy but he was obviously struggling.

“When I saw him struggling I was just trying to get a few serves in and get him running.”