Japan's Kei Nishikori reached the Halle grass-court quarter-finals for the second successive year, recording his 36th win of the season in beating Germany's Dustin Brown 7-5, 6-1.

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Second seeded Nishikori will now face Poland's Jerzy Janowicz, who reached his first grass-court quarter-final in two years by beating 2014 runner-up Alejandro Falla 6-2, 5-7, 6-2.

"It was a great match for me. All the important points I played well," said Nishikori.

"I was just waiting for one chance in the first set because I know I was playing well and he was hitting some great shots, there was nothing I could do. 

"So, I was just waiting for the moment and at 6-5 I took some risks and I did what I had to do. In the second set, I was more confident and everything was going well."

Andreas Seppi broke a four-match losing streak against fifth seed Tommy Robredo, in their 11th meeting to win 6-2, 6-7 (6/8), 6-3.

France's Gael Monfils also made the last-eight by seeing off  Mikhail Kukushkin of Kazakhstan 7-6 (7/1), 6-4 and goes on to face Seppi.