Former World No. 1 Andy Murray reached his second tour-level quarter-final of the season after defeating seventh seed Alexander Bublik 6-3, 7-6(4) at the Boss Open in Stuttgart on Thursday.

"He is predictable in his unpredictability. You are prepared for some amazing shots and then maybe some loose games," Murray said in his on-court interview. "I moved well on the courts well. The court is very dry, so it is nice to move on and hopefully into the weekend the conditions will be a bit calmer and I can play some better tennis."

The three-time major champion now leads Bublik 3-1 in their head-to-head series and has improved to 112-23 on grass surface. Murray, who advanced to the final in Sydney on hard in January, will next play top seed Stefanos Tsitsipas.

The 23-year-old Greek earned his first win on grass since 2019, dispatching Swiss qualifier Dominic Stricker 6-3, 6-4 to reach the quarter-finals.

"I could work a little bit on the percentage of the first serve, which could be higher. Otherwise I was very involved with my footwork," Tsitsipas said. "Being very active on the first ball on the serve, pushing my opponent back. It was a good match."

The world No. 5 has now recorded a tour-leading 35 victories this season, highlighted by his run to the title at the Monte-Carlo Masters in April.

It will be the second career meeting between Murray and Tsitsipas, with the Greek running out a winner in five sets at the US Open in 2021.

Meanwhile, Australian Nick Kyrgios advanced to the quarter-finals in Stuttgart for the second time, moving past fifth seed Nikoloz Basilashvili 6-7(4), 6-4, 6-3.

The 27-year-old, who reached the semi-finals in Germany in 2018, will next face Marton Fucsovics after the Hungarian edged third seed Hubert Hurkacz 7-5, 6-7(9), 6-3.

(With input from AP)