Andy Murray claimed his first win over a top-five opponent since 2016 as he stunned Stefanos Tsitsipas to reach the Stuttgart Open semi-finals.
Murray started his preparations for the grass-court swing with a run to the semi-finals of the challenger at Surbiton.
He knocked off seventh seed Alexander Bublik to reach the last eight in Stuttgart but a meeting with the top seed and world number five represented a much more imposing challenge.
It was one the two-time Wimbledon champion rose to emphatically, winning a first-set tie-break and then claiming the second set in comfortable fashion to cement a 7-6 (7-4) 6-3 win, gaining revenge for his contentious five-set defeat to the Greek at last year's US Open.
Murray's previous win over a top-five opponent came in the ATP Finals six years ago, when he defeated Novak Djokovic in a year that also saw him win Wimbledon.
"I thought I did well. He served unbelievably in the first set," Murray said in his on-court interview.
"I felt like I had very few chances, but when he was creating chances on my serve, I stayed strong.
"I played a really solid tie-break and in the second set, once I was in the rallies, I felt like I was dictating a lot of the points. It was a good performance."
Murray is up to 53rd in the live ATP rankings and is bidding to get back into the top 50 for the first time since 2018.
Standing between him and a place in the final is Nick Kyrgios, who was 7-6 (7-3) 3-0 up when Marton Fucsovics retired from their quarter-final clash.
Matteo Berrettini beat Lorenzo Sonego in three sets, while Oscar Otte won by walkover against Benjamin Bonzi.
At the Rosmalen Grass Court Championships in 's-Hertogenbosch, Daniil Medvedev saw off Ilya Ivashka 7-6 (10-8) 6-4.
Medvedev, who will soon return to world number one when the ranking points from the French Open come into effect, sees the grass-court season as a chance to cement his grip on that spot.
"I don't have many points to defend on grass and I have some to win, so hopefully I can play well, starting here," said Medvedev. "Every round is points and the higher you get, the more you need to step up."
He will face defending champion Adrian Mannarino in the semi-finals, while second seed Felix Auger-Aliassime is into a last-four clash with home hope Tim van Rijthoven after beating Karen Khachanov.