Top seed Roger Federer has survived a major scare at the Western & Southern Financial Group Masters, defeating Robby Ginepri in a hard-fought second round encounter.
The Swiss star struggled in his match-up with the unseeded American but was able to prevail 6-7 (2/7) 7-6 (7/5) 6-0.
The defending champion fired 21 aces but looked surprisingly vulnerable on his serve as he was broken three times.
After a shocking loss to Gilles Simon in the second round at the Rogers Cup last week, Federer faced the possibility of losing his number one ranking for the first time in 234 weeks if he fell to Ginepri, who is ranked 64th in the world.
If Federer does not reach the semi-finals and world number two Rafael Nadal wins the tournament, the Spaniard will take over the top spot.
Nadal has won his last five events since May including victories over Federer at the French Open and Wimbledon finals in a 29-match winning streak.
Federer did not have his killer’s instinct early, allowing Ginepri to break him to make it 5-5 after the Swiss star had broken in the previous game.
Feeding off an enthusiastic crowd, Ginepri went on to force a tie-breaker and win the first five points en route to taking the opening set.
Federer managed to level the set, but not without Ginepri threatening to close out the match in straight sets. Tied at 5-5, the American had his first two break chances turned away by Federer before cashing in on the third after an overrule by the chair umpire.
However, Federer quickly broke right back before taking the second tiebreaker.
The Swiss star made light work of Ginepri in the third set, winning 12 of 13 points on his serve en route to shut out his opponent.
Federer, who improved to 5-0 all-time against Ginepri, will next face 16th seed Ivo Karlovic, who won 6-3 7-6 (7/3) against Argentina’s Jose Acasuso.
Two-time champion Andy Roddick withdrew shortly before his second-round match against Germany’s Philipp Kohlschreiber because of neck and shoulder pain.
The sixth seed’s decision allowed Woong-Sun Jun of Korea to face Kohlschreiber, who advanced 6-2 6-2.
He will meet unseeded Swede Robin Soderling, who upset 12th seed Tommy Robredo of Spain 7-6 (8/6) 6-4.
In an all-French encounter, 11th seed Richard Gasquet was leading Michael Llodra 3-6 6-1 1-0 when Llodra was forced to retire with a left arm injury.
Tenth seed Fernando Verdasco advanced to the second round with a 6-3, 7-5 victory over qualifier Victor Estrella but 15th seed Radek Stepanek went out to Russian Igor Andreev 7-6 (7/4) 6-7 (3/7) 7-6 (7/3).
France’s Florent Serra set up a second-round encounter with Nadal after a 4-6 7-6 (8/6), 6-4 victory over Benjamin Becker of Germany.