Guillermo Garcia-Lopez accounted for Evgeny Donskoy, while Flavio Cipolla and Rajeev Ram also advanced at the St Petersburg Open on Monday.
Seventh seed Garcia-Lopez recovered from an early setback to defeat Russian wildcard Donskoy 2-6 6-4 6-3 in the opening round at the ATP 250 tournament.
The Spaniard hit seven double faults and converted just four of 11 break point opportunities but held on for the win in two hours and 13 minutes.
Garcia-Lopez, ranked 68th in the world, will meet Italy's Paolo Lorenzi or Belarusian qualifier Sergey Betov in the second round.
In other matches, Cipolla overcame Belarusian qualifier Andrei Vasilevski 7-6 (6-4) 7-6 (8-6) in two hours and nine minutes.
The Italian won 71 percent of points on his first serve and will face fifth seed Lukas Lacko of Slovakia or Slovenia's Grega Zemlja next up.
Ram swept aside Germany's Matthias Bachinger, winning 6-4 6-4 in 88 minutes.
Bachinger wasted five of six break point opportunities, allowing Ram to progress to the next round, where he will play Canada's Vasek Pospisil or Russian top seed Mikhail Youzhny.