The luckless Milos Raonic limped out of the Japan Open after suffering another injury setback early in his second-round match against Yuichi Sugita.
Raonic called for a change to the scheduling of the tennis calendar after defeating Viktor Troicki on his return to the circuit in Tokyo this week following a seven-week absence.
The Canadian missed the US Open after undergoing wrist surgery and looked emotional as he walked off court on Thursday, having played just one game against the local favourite before succumbing to what appeared to be a calf problem.
Raonic called for the trainer during the first game and shook hands with Sugita, whose next opponent will be Adrian Mannarino, after failing to hold serve, ambling back to the locker room in discomfort.
David Goffin stayed in the hunt for back-to-back titles but was made to work for a 2-6 7-5 7-6 (7-1) victory over Matthew Ebden.
The world number 11, eyeing a charge for a place in the ATP World Tour Finals, was crowned Shenzhen Open champion last weekend and recovered from losing the first five games against Ebden in a one-sided first set to reach the quarter-finals.
Fourth seed Goffin will take on Richard Gasquet, a 6-0 7-6 (7-5) winner against Lu Yen-hsun, while Steve Johnson's reward for toppling Alexandr Dolgopolov is a meeting with Diego Schwartzman.