Second seed Albert Ramos-Vinolas progressed to the quarter-finals of the Kremlin Cup on Wednesday with victory over Evgeny Donskoy.
Ramos-Vinolas claimed a 6-4 6-7 (7/4) 6-4 success in just under three hours and joins fellow Spaniard and top seed Roberto Bautista Agut in the last eight.
Earlier, qualifier Alexander Bublik beat fellow Russian Konstantin Kravchuk 1-6 6-3 6-3 to secure a second-round match against Bautista Agut.
The Spaniard, runner-up in the Shanghai Masters last week and at the Moscow event for the past two years, is continuing his quest to reach the season-ending ATP World Tour Finals in London.
Number seven seed Paolo Lorenzi is out after the Italian was beaten by compatriot Fabio Fognini 7-5 4-6 6-1, who will be joined in the last eight by Frenchman Stephane Robert following his 7-5 6-1 victory over Czech player Lukas Rosol.
Tuesday's other matches saw number eight seed Andrey Kuznetsov and Damir Dzumhur advance past Guido Pella and Karen Khachanov respectively.
At the Stockholm Open, third seed Ivo Karlovic of Croatia survived a scare to come from behind and see off 18-year-old Swedish wildcard Mikael Ymer 4-6 6-4 6-4 and reach the quarter-finals.
Sixth-seeded Jack Sock is through to round two after beating Malek Jaziri of Tunisia 3-6 6-3 7-6 (7/5), though another American, John Isner, was eliminated in straight sets by Juan Martin del Potro.
Earlier, qualifier Jurgen Zopp of Estonia overcame a difference of 118 world ranking places as he knocked out Germany's Benjamin Becker 6-3 6-4 to set up a second-round contest against number two seed Grigor Dimitrov.
Alexander Zverev's tournament will continue too after he saw off Adrian Mannarino 7-5 6-4.
In Antwerp, third seed Richard Gasquet of France dropped just six games to beat Inigo Cervantes in straight sets to move into the quarter-finals of the European Open.
Fourth seed Pablo Cuevas of Uruguay also progressed with a 6-4 7-6 (7/4) win over Slovak qualifier Jozef Kovalik, while Italian Andreas Seppi beat Robin Haase of the Netherlands 7-5 7-5.
Frenchman Gilles Simon defeated German qualifier Yannick Maden 6-3 6-2 in their first-round contest, American Taylor Fritz had to come from a set down to beat Belgian wildcard Joris De Loore 3-6 6-4 6-4, while Steve Darcis did likewise to knock out Benoit Paire 6-7 (6/8) 6-1 6-4.
Source: PA
