Munich - Juan Martin del Potro has won consecutive clay-court matches for the first time in four years by seeing off Germany's Jan-Lennard Struff 6-2, 3-6, 6-3 to make the Munich quarter-finals on Thursday.
The injury-plagued Argentine, who was the 2009 US Open champion, broke serve seven times. The last time Del Potro won consecutive matches on clay was at the 2012 French Open.
He will face fourth seed Philipp Kohlschreiber, who defeated fellow German Florian Mayer 6-4, 6-4 for a spot in the semifinals.
"My movement on the court isn’t the best right now, but the important part is to win matches on clay for the first time in many years,” said Del Potro who holds a 6-0 lead in career meetings against Kohlschreiber.
Top seed David Goffin hit 10 aces in a 5-7, 6-2, 6-3 win over Victor Estrella Burgos and next faces German teenager Alexander Zverev.
Zverev won his 15th match of 2016 with a 6-3, 6-4 victory over Lukas Rosol of the Czech Republic.
Fifth seed and 2014 finalist Fabio Fognini beat Mikhail Kukushkin 6-3, 7-5 and next faces lucky loser and world number 139 Jozef Kovalik – who defeated qualifier Igor Sijsling 6-3, 6-4 – for a place in the semifinals.