Top two seeds Pablo Carreno Busta and Richard Gasquet both progressed to the quarter-finals of the Estoril Open in straight sets, on a day that saw Juan Martin del Potro withdraw from the tournament.

Fifth seed Del Potro pulled out in order to travel back to his native Argentina following the death of his grandfather.

Meanwhile, top seed Carreno Busta claimed his first win over compatriot Tommy Robredo, last year's beaten finalist winning 7-6 (7-5) 7-5.

A rematch of the final follows for Carreno Busta, with another countryman in Nicolas Almagro lying in wait after a 6-1 6-2 defeat of home hope Gastao Elias.

Gasquet's return from appendicitis at the Barcelona Open saw him beaten by Yuichi Sugita, but the Frenchman looks good this time around, reaching the last eight with a 6-1 6-4 victory against Carlos Berlocq.

Kevin Anderson is next up for Gasquet after the South African needed three sets to see off qualifier Joao Domingues 5-7 6-3 7-5.

At the BMW Open, second seed Roberto Bautista Agut avoided a shock defeat to Marius Copil, coming from a set down to beat the Romanian 4-6 7-6 (7-3) 7-5.

Copil served for the match at 5-3 in the decisive set and was two points from pulling off the upset, only for the Spaniard to win four games in a row to progress to the quarters.

Yannick Hanfmann awaits Bautista Agut in the last eight after the qualifier stunned eighth seed Thomaz Bellucci 7-6 (7-5) 4-6 7-5.

Third seed Alexander Zverev was a 6-4 6-4 winner over Jeremy Chardy, setting up an all-German quarter-final following Jan-Lennard Struff's 6-4 7-5 triumph against another compatriot in Tommy Haas.