HALLE WESTFALEN, GERMANY (AFP) - Russia's Andrey Rublev admitted he had to raise his game to reach the semi-finals of the ATP grass court tournament in Halle by beating 2011 champions Philipp Kohlschreiber on Friday (June 18).

Rublev is the last remaining seed in the Halle draw after Roger Federer and world number two Daniil Medvedev were among the big-name casualties in the early rounds.

The 23-year-old Russian held his nerve in the first set tie-breaker to earn a 7-6(4), 6-2 quarter-final win over Kohlschreiber to reach his sixth semi-final of 2021 on the ATP tour.

"I am happy with my performance to reach the semi-finals for the first time (in Halle)," said Rublev.

"The first set was really tough. He was 3-0 up in the tie-break and I came back, which was the key.

"After the first set, I think he mentally went down and I was pumped up."

On Saturday, world number seven Rublev, will face Georgian qualifier Nikoloz Basilashvili, 30th in the world, who beat Lloyd Harris of South Africa 6-4, 7-6 (7/5).

Canada's Felix Auger-Aliassime continued his impressive form on grass by reaching the semi-finals with a 6-3, 6-2 victory over Marcos Giron of the USA.

"I've been playing well these past two weeks, believing in myself a lot and dominating my service games," said Auger-Aliassime, who converted his first match point after firing down his 14th ace of the match.

The 20-year-old has built some momentum in Halle having beaten his childhood idol Federer in the second-round and will play either France's Ugo Humbert or Sebastian Korda of the USA in the other semi-final.

"I received a lot of messages and attention, and those kinds of things can be tricky," he admitted.

"They can take you out of your 'zone' and your focus on the tournament."

Auger-Aliassime is bidding to end a streak of eight losses in ATP finals in the last two years, including last week's Stuttgart grass court tournament.