Rublev digs deep to reach Halle semi-finals
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 ATP tour.
"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, currently 30th in the world, who later beat Lloyd Harris of South Africa 6-4, 7-6 (7/5) in their quarter-final on Friday.