Andy Murray upset top seed Stefanos Tsitsipas 7-6 (7/4), 6-3 on Friday for a place in the Stuttgart semi-finals as the former world number one claimed his first top five win since 2016.
The 35-year-old said the strong winds, which featured in his first two wins this week, were missing as he put on a top serving performance to defeat the world number five who won their only previous match at the US Open last year.
"We had good conditions," the 68th-ranked Murray said after victory on his third match point.
"We both served very well for most of the match. There were very few chances either way, neither of us created many opportunities."
The three-time Grand Slam champion said his tiebreak success helped power him through the second set to the victory.
"I had momentum going into the second set. It was important for me to try and dictate when possible," added Murray.
"It was much easier to play today... with very little wind I did well, I was consistent for the whole match.
"This was my best serving performance of the week."
Murray last reached a Tour semi-final in January in Sydney on his way to the final.
Next up for the three-time major winner is an intriguing clash with Australian firebrand Nick Kyrgios.
On Saturday, Murray will take on Kyrgios after Marton Fucsovics had to quit with back pain when trailing 7-6 (7/3), 3-0.
"I didn't take him lightly, he knows how to play on grass," said world number 78 Kyrgios.
"I was not feeling it today from the back of the court, but I was serving well. Hopefully I'll bring that tomorrow against Andy."
Kyrgios stands 1-5 against Murray but won their last meeting on grass at Queen's Club in 2018.
German Oscar Otte advanced to the last four when French opponent Benjamin Bonzi was unable to take to the court due to stomach pains.
Matteo Berrettini moved into the final four with a 3-6, 6-3, 6-4 win over fellow Italian Lorenzo Sonego.
Berrettini, only just back after three months out due to hand surgery said he would have preferred to go through in straight sets.
"He played well and I'm still not back to my best shape," the world number 10 said. "I was not serving or returning that well.
"But I expected my first tournament would be tough. I told myself to fight in the second and third sets and hope that something good comes from it."
Last year's Wimbledon runner-up Berrettini, who will lose his world top 10 standing with no ranking points to be awarded at the All England Club following the ban on Russian and Belarusian players, said he will just have to make do with his grass preparation.
"I still have time to prepare for Wimbledon, but it depends on how many matches I play. I'm really glad that I won today.
"It's different preparing on grass, no one has played on it for a year, it's the first time for everyone."
Results from the ATP tournament in Stuttgart on Friday (x denotes seeding; players representing Russia and Belarus are banned from competing under the name or flag of their countries):
Andy Murray (GBR) bt Stefanos Tsitsipas (GRE x1) 7-6 (7/4), 6-3
Nick Kyrgios (AUS) bt Marton Fucsovics (HUN) 7-6 (7/3), 3-0 - retired
Oscar Otte (GER) bt Benjamin Bonzi (FRA) - walkover
Matteo Berrettini (ITA x2) bt Lorenzo Sonego (ITA x6) 3-6, 6-3, 6-4