World number one Roger Federer [Images] reached the last 16 of the Rome Masters with a nervy 6-3, 7-6 win over Italian wildcard Potito Starace in Rome on Wednesday.

The Swiss, who has not won the Rome title in five previous visits, romped through the first set but lost his concentration, rhythm and serve after questioning a line call in the second.

Urged on by the home supporters, Starace threatened to fight his way back into the contest.

Federer, however, broke back and held serve in a game that ran to six deuces and then played a near-perfect tiebreak to set up a third-round clash with 14th seed Radek Stepanek.

"It always seems I find my best shots -- my best serve, my best forehand -- when I need them and I'm pleased about that because if it had gone to a third set it would have been very difficult," said the top-seeded Federer.

"The match would have been a lot easier if he hadn't had all that support. I really had to work hard to focus on my game but I'm very happy with the way things went today."

Champion Rafael Nadal [Images] racked up his 49th straight win on clay to move closer to Guillermo Vilas's 1977 record of 53 consecutive wins on the surface by beating Italian number one Filippo Volandri 6-1, 6-2.

However, the second-seeded Spaniard insisted he was taking one game at a time, saying: "I'm just thinking about playing [Tim] Henman in the next round".

IMPRESSIVE PERFORMANCES

While Federer and Nadal continue to be strong favourites, several other leading players gave impressive performances.

Fourth-seeded Argentine David Nalbandian gave a businesslike display to beat Frenchman Paul-Henri Mathieu 6-2, 6-4 and set up a meeting with Spanish qualifier Alberto Martin, who knocked out 13th seed Nicolas Kiefer of Germany [Images] 6-3, 7-6.

The man Federer replaced as world number one, fifth-seeded American Andy Roddick [Images], also reached the last 16 after coming through a see-saw encounter with Marcos Baghdatis 3-6, 6-1, 6-2.

The American got his revenge over the Cypriot who beat him on the way to Australian Open final in January and next plays Greg Rusedski [Images].

The Briton followed up his first-round win over claycourt specialist Tommy Robredo with a 7-6, 6-4 victory against home favourite Stefano Galvani.

"I served absolutely terribly for a set and a half," said Roddick. "But somehow I just found a way to get through it. So that's satisfying, I guess."

Like Roddick, Rusedski is more at home as a serve-volleyer on grass than slugging it out on clay.

"If you had taken a poll in the locker room on round of 16 match-ups, I don't think Rusedski and I would have been one of them," joked Roddick, who has made early exits in his last three visits to the Italian capital.

"But weirder things have happened. I'm sure we're both looking at it as a good opportunity.

"And, you know, you don't get to the third round by luck. To beat Robredo on clay and then an Italian in their home country is no easy task".

• Complete tennis coverage
• All you want to know about Sania Mirza