Halle Westfalen - Andy Murray's Wimbledon doubles partner Pierre-Hugues Herbert is hoping to meet Roger Federer in the last four of the ATP event in Halle after reigning champion Borna Coric retired hurt in the quarter-finals on Friday.
Herbert won the first set 7-5 against Coric before being granted passage to the semi-finals when the Croatian retired with what appeared to be a back problem.
"It is sad for Coric because he won here last year. I noticed that he was hurt because his serves got slower," said Herbert.
The 28-year-old Frenchman faces the prospect of a first-ever meeting with Federer, who plays Roberto Bautista Agut in his quarter-final later on Friday.
"It would be unbelievable for me to face Roger. I have played against Nadal, against Djokovic, against Murray, but never against him," said Herbert.
World number five Alexander Zverev suffered a surprise 6-3, 1-6, 6-7 (3/7) quarter-final defeat by Belgium's David Goffin.
Home favourite Zverev was playing with a swollen knee after slipping and hurting himself in the first round, and the Halle crowd watched on in dismay as he struggled to find his rhythm against world number 33 Goffin.
The 22-year-old served nine double faults in a rollercoaster match, and survived two match points in the third set before ultimately losing in the tiebreaker.
The defeat compounds a disappointing grass season so far for Zverev, who suffered another early exit on home soil in Stuttgart last week at the hands of compatriot Dustin Brown.
The German will be hoping to rediscover his form and fitness in time for the beginning of Wimbledon on July 1.
Goffin will face Italian talent Matteo Berrettini in the semi-finals on Saturday.
Rising star Berrettini continued his excellent 2019 form with a 6-2, 7-6 (7/4) victory over Russian third seed Karen Khachanov.
Berrettini, 23, won his third ATP title of the season in Stuttgart last week, and has soared up to 22 in the world rankings this year.
"I have worked hard and realised that I have the level to play in these kinds of matches," he said.
Results from the ATP tournament in Halle on Friday (x denotes seeding):
Quarter-finals
Pierre-Hugues Herbert (FRA) bt Borna Coric (CRO x4) 7-5 - retired
Matteo Berrettini (ITA) bt Karen Khachanov (RUS x3) 6-2, 7-6 (7/4)
David Goffin (BEL) bt Alexander Zverev (GER x2) 3-6, 6-1, 7-6 (7/3)