Marin Cilic and David Goffin each needed three sets to reach the quarter-finals of the Rotterdam World Tennis Tournament as the seeded pair were tested in the way to victory.
Top seed Cilic, who had won just one match this season before starting the indoor week, outlasted comeback candidate and fellow Croat Borna Coric 6-1 2-6 6-4 on Thursday.
Belgium’s Goffin, the third seed, rallied and took more than two hours to beat Robin Haase 5-7 6-4 6-4. Haase was competing in Rotterdam for the ninth time but reached his last quarter-final in 2008.
Czech fourth seed Tomas Berdych, the 2014 champion, hammered Richard Gasquet 7-6 (7-4) 6-1 as he powered through comfortably in straight sets.
Cilic beat younger countryman Coric for the third time in as many seasons after leading 5-0 in the first set in a match which evolved into a struggle for the world No.7.
“I was playing extremely well, using every opportunity I had,” Cilic said. “It’s always tough to play a countryman and Borna has been doing well in his comeback (from 2016 knee surgery).
“It was not an easy match, even after winning the first set quickly. Borna has proved himself as a next-gen player.”
Thursday’s late matches saw victories for both number two seed Dominic Thiem and Grigor Dimitrov.
Austrian Thiem came through in straight sets 6-4 7-6 (7-4) against Gilles Simon of France, while it was a similar story for fifth-seeded Bulgarian Dimitrov as he saw off Denis Istomin of Uzbekistan 7-6 (9-7) 6-1.
Dimitrov will meet Goffin for a place in the semi-finals while Thiem will take on French qualifier Pierre-Hugues Herbert.