Defending champion David Ferrer was pushed to three sets by Czech Lukas Rosol in his opening match at the Paris Masters on Wednesday before easing into the last-16, 6-0, 2-6, 6-3.
Rosol, who is part of his country's squad to face Serbia in the Davis Cup final on November 15, appeared to be on the receiving end of a rout before fighting back to give Ferrer a scare when he won the second set 6-2.
However, the experience of the 31-year-old Grand Slam finalist proved decisive in the final frame as Ferrer consistently put pressure on the Rosol serve and was rewarded with a third round tie against Frenchman Gilles Simon.
The Nice native, a semi-finalist loser last year in Paris against Poland's Jerzy Janowicz, defeated Nicolas Mahut in a marathon 6-4, 6-7 (5/7), 7-6 (7/3) second round matchup.
Simon led 4-1 in the final set before an injury break forced upon Mahut appeared to revive the taller Frenchman.
However, when the conclusion went to a tie-break, it was Simon who was strongest and finally closed out the longest match of the tournament for a rewarding victory.
"It was very difficult for both of us and we both had problems," said a relieved Simon.
"It's the last tournament of the year and we're ready to die out there but I'm very, very happy to have won this match."
Argentine fourth seed Juan Martin Del Potro made it 14 wins from 15 matches since the US Open, as he improved his record to eight victories in ten outings against returning Tour veteran Marin Cilic.
The 25-year-old, who won his fourth ATP title of the year last weekend at Basel, withstood 19 aces from his opponent before closing out a tense encounter 6-4, 7-6 (7/3) against the Croatian.
Cilic is playing his first tournament since Wimbledon, following a shortened doping ban.
"This is a really big tournament and very important for all the players so I'm very happy to have won and hope to go far in the tournament," said Del Potro.
"It's fantastic to be back in Paris because I missed the French Open this year and a lot of people have come out to support me," he added.
Swiss Stanislas Wawrinka increased his chances of not only trying to finish the year inside the top ten for the first time, but also of protecting his eighth place ranking when he ground down Spaniard Feliciano Lopez 6-3, 3-6, 6-3.
A tight match with just three breaks of serve in total swung the 2008 Olympic doubles champion's way in the final frame, thanks to his booming serve that produced 19 aces.
This year's US Open semi-finalist now faces 13th seed Nicolas Almagro following the Spaniard's comfortable 6-4, 6-3 victory over Croatian Ivan Dodig.
Earlier, big-serving American John Isner bombarded Polish qualifier Michal Przysiezny with 27 aces on the way to a 7-6 (7/3), 4-6, 6-3 second round win.
Awaiting the topped ranked US player is six-time Grand Slam winner Novak Djokovic.
Rafael Nadal is next on centre court as he makes his much anticipated tournament debut against fellow Spaniard Marcel Granollers, while his long-time rival Roger Federer is also in action.
The Swiss record Grand Slam holder needs to beat South African Kevin Anderson to seal his place at next month's ATP World Tour Finals for the 12th straight season.
Canadian Milos Raonic, who faces Dutch qualifier Robin Haase in the final evening match-up, faces a daunting challenge in his bid to overtake Richard Gasquet, Wawrinka or Federer and gatecrash the World Tour Finals.
The powerful serving, Montenegro-born 22-year-old, must reach the final in Paris to have a chance of qualifying.