A heavy schedule which included three qualifying matches hasn’t stopped Jiri Vesely make his second top-level tennis semi-final.

The 21-year-old took just 61 minutes to dispatch Donald Young of the United States 6-2 6-3 at the Heineken Open in very warm conditions in Auckland.

It was his sixth match this week but Vesely said his body was holding up well.

“This morning when I woke up I was a little bit tired from the match from last night, but I’m trying to stay positive,” he said.

“This is my best tournament to date, my best start for the season, so if you are on fire then you don’t really matter about your fitness.”

Vesely improved his ranking from 84 to 66 last year despite an ordinary first half of the year, and his second ATP Tour semi-final appearance should push him close to the top 50.

Vesely’s semi-final opponent will be South African fourth seed Kevin Anderson, who accounted for eighth seeded American Steve Johnson 6-4 7-6 in their quarter-final.

One of the men Vesely beat in qualifying, 20-year-old Lucas Pouille of France, is also through to the semi-finals.

Pouille got into the tournament to replace the injured Tommy Robredo as a lucky loser, and only got that because fellow Frenchman Stephane Robert chose to prepare for the Australian Open rather than take a chance at a lucky loser spot.

Pouille then stepped in, beat New Zealander Michael Venus in the second round and then thrashed Albert Ramos-Vinalos of Spain 6-3 6-2 in the quarter-finals.

He plays fellow Frenchman Adrian Mannarino in the semi-finals on Friday after Mannarino, the world number 44, beat Alejandro Falla of Colombia 6-3 6-1.

Mannarino has trained with Pouille this year but that won’t happen again before Friday’s match.

“We’re still going to speak together but we’re not going to practise tomorrow, we’re not going to warm up together, and we’ll try to concentrate on our match,” Mannarino said.