Russia’s Daniil Medvedev beat compatriot Andrey Rublev to reach the semi-finals at the Australian Open for the first time.
The fourth seed outlasted Rublev 7-5 6-3 6-2 as his eighth-ranked opponent struggled in the 29C temperatures at Melbourne Park.
Medvedev has won all 11 of his matches against top 10 players since the US Open in September 2020.
He will play either Rafael Nadal or Stefanos Tsitsipas next.
ATP Finals champion Medvedev goes into the semi-finals on a 19-match unbeaten streak.
“It was one of the best matches I’ve played lately” Medvedev said.
“This match is really unbelievable.”
Medvedev called for the trainer after the match as he struggled with cramp in his left thigh.
Rublev has lost his past four matches against his good friend Medvedev, but the two were closely matched in a competitive first set.
They traded breaks before Medvedev capitalised, taking the opener as Rublev was broken to love.
Rublev in particular struggled with the humidity, at one point sitting down on his box of towels after a gruelling 43-shot rally.
Both players were breathing deeply as the match progressed but it was Medvedev, who has improved his fitness in his rise to the top 10, who dealt with the conditions better.
He sealed victory on his first match point to reach his third career Grand Slam semi-final.
He lost to Nadal in a thrilling five-set US Open final in 2019 but he holds a 5-1 winning record over Greek Tsitsipas.
Medvedev also beat Spanish second seed Nadal in the last four of the ATP Finals in October.