Jerzy Janowicz stepped up his return from injury by reaching his first ATP quarter-final of 2017 with a 7-6 (7-4) 6-3 victory over second seed Grigor Dimitrov at the Stuttgart Open.

The Pole was plagued by knee problems in 2016 and is currently ranked 155 in the world, having hit a career high of 14 in 2013.

But the 26-year-old showed glimmers of a return to form as he ousted world number 12 Dimitrov in straight sets on Thursday.

"This is an important moment for me," he said. "I'm really happy, but I cannot stop fighting for more wins.

"I'm trying to be back in the place where I was two years ago and I'm really fighting.

"I was injured, I was struggling a little bit, but now I'm on the way."

The result, and the elimination of Roger Federer by Tommy Haas on Wednesday, leaves Tomas Berdych as the top remaining seed in the draw, with the Czech having beaten Bernard Tomic 7-6 (7-4) 6-2 to reach the last eight.

Berdych will now face Feliciano Lopez, who knocked out Jeremy Chardy, while Benoit Paire awaits Janowicz following his victory over Peter Gojowczyk.

Top seed Marin Cilic came from behind to beat Janko Tipsarevic 6-7 (6-8) 6-2 6-4 in the best quarter-final of the day at the Rosmalen Grass Court Championships.

There were also wins for Ivo Karlovic and Daniil Medvedev, who face each other in the last four, while the retirement of Alexandr Dolgopolov means Vasek Pospisil progresses to meet Cilic.