World number one Roger Federer recovered from an early fright to beat Belgian Olivier Rochus 4-6 6-3 6-2 in the first round of the Estoril Open claycourt event.

The Swiss player, who has made his worst start to a season since 2000, failed to convert a series of break points and also produced several unforced errors as baseliner Rochus took the opening set.

Federer then showed his class to claim the next two sets, clinching victory with his 17th ace.

"It was disappointing the way I played the first set but what can you do?", Federer said after the two-hour match on centre court.

"You have to wake up in the second set and adjust a few things and in the third I started to get the upper hand from the baseline, which was key."

Federer's sixth consecutive win over world number 77 Rochus earned a second-round meeting with Victor Hanescu of Romania.

The 12-times grand slam winner, who recently hired claycourt expert Jose Higueras of Spain as coach, has yet to win a tournament this season.

"I had good timing with my serving and good timing moving around the court but my worst moments came with the unforced errors," said Federer of Tuesday's match.

Rochus was 5-2 down in the second set when he needed treatment on his injured right shoulder.

"In the first set I played very good tennis and Roger was missing a lot," said the Belgian.

"Roger began to play better and better and as soon as he was leading 5-2 in the second I realised it would be very difficult.

"I made two double faults and from then on he was on top."

Second seed and former champion Nikolay Davydenko was untroubled after arriving from a Davis Cup win in Moscow, dispatching Austrian Jurgen Melzer 6-3 6-1 to ease into the second round.

Davydenko won the 2003 title and reached the final two years ago, but has also exited three times in the first round at the Estadio Nacional.

Portugal's Rui Machado surprised ailing third seed Ivo Karlovic, advancing to a surprise win through retirement when the Croatian trailed 6-4 1-0 with a knee injury.

In the women's event, top-seeded Italian Flavia Pennetta defeated Yvonne Meusburger 4-6 6-0 6-2 while number two Maria Kirilenko faced a battle before stopping Swiss teenager Sandra Vogele 6-4 6-7 6-1.

Reuters