Alexander Zverev made home advantage count as he battled through to the quarter-finals of the German Tennis Championships with a straight-sets win over Federico Delbonis.

After a shock first-round exit at Wimbledon, world number five Zverev - featuring in the tournament in his hometown for the first time since 2016 - has rediscovered his form on clay. 

He had to overcome a resilient opponent in Delbonis in humid conditions on Thursday, coming out on top 6-4 7-6 (7-2) to join world number four and top seed Dominic Thiem in the last eight.

Zverev will face Filip Krajinovic next, with the Serbian having beat 2016 champion Martin Klizan 6-7 (6-8) 7-5 6-1. 

Seventh seed Jan-Lennard Struff suffered a surprise defeat to Pablo Carreno Busta, who will meet Fabio Fognini next after the Italian beat Rudolf Molleker 7-5 6-4.

Meanwhile, the seeded players also dominated in the Swiss Open Gstaad - Roberto Bautista Agut, Dusan Lajovic, Joao Sousa and Pablo Andujar all progressing to the quarter-finals.

Bautista Agut, a runner-up at the tournament last year, saw off compatriot Jaume Munar 7-6 (9-7) 6-4, while third seed Lajovic required three sets to edge past Denis Istomin.

Sousa found victory easier to come by against Gian Marco Moroni, while Andujar saw off a second-set fightback from Taro Daniel to triumph 6-1 3-6 7-6 (7-2).