Joao Sousa's hopes of retaining his Estoril Open crown came to an end on Thursday after he was beaten in straight sets.
The Portuguese was unable to cope with David Goffin in their last-16 tie, the fourth seed running out a comfortable 6-3, 6-2 winner after 80 minutes, much to the disappointment of the home crowd.
Goffin's progression sets up a clash with Tunisian Malek Jaziri, who overcame Leonardo Mayer of Argentina in straight sets, 7-6 (7-2), 6-1.
Last year's losing finalist Frances Tiafoe progressed in the last match of the day, the eighth seed needing to come through a final-set tie-break to eventually beat Japan's Yoshihito Nishioka 2-6, 6-3, 7-6 (7-5).
The world number 31 will go up against Pablo Cuevas - a 6-2, 7-5 winner in his meeting with Filippo Baldi - next for a place in the semifinals.
Khachanov crashes out
At the BMW Open in Munich, three-time champion Philipp Kohlschreiber knocked out second seed Karen Khachanov to reach the last eight.
German Kohlschreiber is making a habit of causing upsets this year - he defeated world number one Novak Djokovic in the third round at Indian Wells - as he triumphed 7-6 (8-6), 6-4 after one hour and 49 minutes on court.
His reward is a match with Matteo Berrettini, the Italian having defeated Denis Kudla in straight sets.
While Khachanov crashed out, there was better news for fellow seeds Roberto Bautista Agut (4) and Guido Pella (7), who will face each other in the next round after respective victories over Rudolf Molleker and Taro Daniel.