Roger Federer overcame a brief second-set wobble to beat Malek Jaziri 6-3 7-5 on Thursday and remain on course for a ninth title at the Gerry Weber Open.
Seeking a first tournament success in 2016, as well as his fourth in a row in Halle, Federer claimed a solitary break to take the opening set against Jaziri.
The world number 64 responded by breaking his illustrious opponent to love en route to a 3-0 lead in set two.
However, Federer soon regained control to set up a quarter-final meeting with David Goffin, the fifth seed.
Goffin enjoyed a lucky escape against Sergiy Stakhovsky, who looked set to triumph in straight sets before sustaining an injury in a fall.
Stakhovsky was serving for the match at 6-4 5-4 when he was hurt. Goffin duly capitalised to take the second set 7-5 and was 2-0 up in the decider when his opponent retired.
Philipp Kohlschreiber beat Ivo Karlovic 6-7 (7-9) 6-4 7-5 to move up to joint third in the list of Germany's most prolific match-winners on the ATP World Tour. Kohlschreiber's 385th win puts him alongside Michael Stich, with Boris Becker and Tommy Haas the only Germans to have recorded more wins.