Switzerland's Roger Federer overcame a stirring first-set challenge from Thierry Ascione to ease into the third round of the Paris Masters.
The number three seed beat the French qualifier 7-6 (7-5) 6-1 on Wednesday.
It was a tense opening set as Federer's unforced errors allowed his opponent to reel off three service games to love.
But he held on before cruising through the second set to book a third round tie against either Martin Verkerk from Holland or Slovakia's Dominik Hrbaty.
The Wimbledon champion attributed his shakey start against Ascione to a back problem he picked up during the Swiss Indoors last week.
"I didn't practice for four days and I wasn't sure I was going to make it. I couldn't force it too much... I kept the points short and didn't use up too much energy," he said afterwards.
"Everything went better in the second set, particularly my service and return, and I can play full out for the rest of the tournament."
Federer is currently in a three-way tussle with world number one Juan Carlos Ferrero and Andy Roddick to finish top of the year-end rankings.
Earlier, fourth seed Guillermo Coria safely advanced to the next round with a 6-3 3-6 6-3 win over Feliciano Lopez.
Coria next meets Andrei Pavel of Romania who beat Felix Mantilla of Spain 7-5 7-6 (8-6).
Jonas Bjorkman of Sweden is also in round three following a 6-4 6-1 victory over Nicolas Lapentti, a last-minute replacement for David Nalbandian.
The sixth seed pulled out on Wednesday morning with a left wrist injury.
But 11th seed Sjeng Schalken suffered an upset losing to French qualifier Gregory Carraz 6-4 2-6 6-3.
Jiri Novak, the 14th seed, looked in trouble when he allowed an inspired Fabrice Santoro to level their second-round encounter.
However, Novak stormed through the decider to clinch a 6-4 4-6 6-0 victory.
An out-of-sorts Rainer Schuettler survived a scare before seeing off James Blake 4-6 6-2 6-3.