Dominic Thiem needed a final-set tie-break to reach the semi-finals of the St. Petersburg Open at the expense of Daniil Medvedev and Stan Wawrinka saw off defending champion Damir Dzumhur.
Top seed Thiem, in the hunt for a third title of the year, was pushed all the way by home contender Medvedev but sealed a 6-2 3-6 7-6 (7-2) victory.
The world number eight broke three times and served 10 aces as he set up a last-four encounter with Roberto Bautista Agut.
Thiem said: "I'm very sorry that I beat a Russian guy, but I think it was a great match from the beginning until the end. [A] tie-break in a deciding set is always lucky, so I'm lucky that I won."
Wawrinka showed further signs that he is getting back to something like his best with a 6-3 6-4 defeat of 2017 winner Dzumhur.
The three-time grand slam champion won 71 per cent of points on his first serve and broke three times to advance.
Bautista Agut got the better of third seed Marco Cecchinato 7-6 (7-0) 6-3, while Martin Klizan will face Wawrinka after ousting Denis Shapovalov 3-6 7-5 6-3.
Meanwhile, Kei Nishikori moved a step closer to a first tour-level title since 2016 with a 6-3 4-6 6-4 win over Nikoloz Basilashvili in the quarter-finals of the Moselle Open.
Gilles Simon finally came out on top in an all-French encounter with Richard Gasquet in Metz for the first time, winning 7-6 (7-4) 6-2 to end a run of eight consecutive losses against his compatriot and will take on Radu Albot, who beat Ricardas Berankis.
Matthias Bachinger will be Nishikori's semi-final opponent after he sent fellow German Yannick Maden packing.
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