Roger Federer saw off a strong first-set challenge from Ivo Karlovic to book his place in the third round of the Rome Masters with a 7-6 (7/4) 6-3 win.
The Croatian matched Federer stroke for stroke in the first set showing he has more to his game than a big serve, but Federer edged a tie-break to take the lead.
And Karlovic could not maintain his level in the second as Federer broke twice to take it 6-3.
Karlovic began well, getting into the groove on his serve and earning two break points in the third game with a succession of strong returns.
The Swiss won four points in a row to hold though and seldom looked like giving his opponent another chance.
The world number one earned break points of his own in game eight but a display of big serving got the 6ft 10in Croat out of trouble.
Karlovic defended a set point with his eighth ace to force a tie-break, of which Federer took control with a thundering return to go 6-4 up.
A backhand pass had too much heat for Karlovic and Federer took the breaker 7/4.
Karlovic saved two break points in game five of the second set but could do nothing about the third when a deep Federer forehand clipped the baseline.
And that proved to be a lead he would not relinquish as he broke again in game nine to clinch victory.
Federer admitted afterwards Karlovic's strong start put him on the back foot.
‘It's very difficult,’ he said on Sky Sports Xtra. ‘You feel a lot of pressure - I was down a couple of break points and that made it hard.
‘You don't get a look on his serve and you start to get a little nervous.
‘I was very happy to get that first break (in the second set). He's a good player.
‘The thing about Ivo is he serves so accurate and he's got such a great trajectory that even if you read it it's hard to get it back.
‘It's a great challenge and as long as you don't get frustrated you can have fun.’
Federer was given a helping hand in his quest for the Rome title when second seed and defending champion Rafael Nadal suffered a surprise loss to Spanish compatriot Juan Carlos Ferrero in the second round.
Federer admitted he felt some sympathy for his great rival, for whom it was just his second defeat on clay in his last 105 matches.
‘It's sad to see Rafa lose,’ said Federer. ‘He's had such a great streak.
‘All of a sudden I feel like there's room to breathe here in Rome.’
Federer faces a quarter-final clash with Radek Stepanek, who ran out a 6-4 1-6 6-3 winner over Luis Horna on Thursday.
Third seed Novak Djokovic survived a second-set scare to take his place in the last eight with a 6-3 3-6 6-3 success over Russia's Igor Andreev.
The reigning Australian Open champion will next face Spaniard Nicolas Almagro, who was handed a walkover after Fernando Gonzalez pulled out of their third-round meeting with a right leg injury.
