Rafael Nadal yesterday revealed that, three months into his comeback from a serious knee injury, he is operating at about half-speed.

That is not a particularly comforting revelation for his principal rivals, Novak Djokovic, Roger Federer and Andy Murray, given that the Mallorcan maestro has reached the final of all seven events he has entered this year, winning five of them. He is not exactly struggling.

Nadal arrived in Rome yesterday, fresh from victory in Madrid and chasing a seventh title in the Italian capital. He claimed the left knee that has held up well in tournament play so far is far from 100%.

"I am not practising a lot," Nadal admitted. "I just practised 50 minutes today. One year ago, one day like today I would practise close to two hours. But it seems like that's not decisive because I am able to compete well and keep having chances against the best players and keep having chances to win. The important thing is to adapt yourself to the conditions and accept your situations. From that point, try to do as good as you can.

"For me, to be here competing another time is fantastic news, I am enjoying it. And even if I am not able yet to do all the things that I want to do, it's much more than what I dreamed four or five months ago, so I'm happy for that."

Nadal said he struggled for form in his first few events back. "I didn't play well in Monte Carlo", where he lost in the final to Djokovic, and played only "normal" in Barcelona, where he won.

But the seven-times French Open champion said the way he played in Madrid, where he beat Stanislas Wawrinka in the final, gave him more confidence as he moves into the most important two months of his season.

While Nadal opens his title bid against the erratic, but occasionally brilliant, Fabio Fognini of Italy today, world No.2 Murray faces Marcel Granollers of Spain. After losing in round three in Monte Carlo, the Scot, who celebrates his 26th birthday today, reached the quarter-finals in Madrid and will be trying to improve again at a venue where he made the last four in 2011.

World No.1 Djokovic, who is seeking another title after a surprise early defeat in Madrid, looked back to his best as he beat Albert Montanes 6-3, 6-2, while Federer was due to open his title bid last night against Italy's Potito Starace.

Laura Robson's star is very much on the rise but her hopes of a second Williams scalp ended last night as she was beaten 6-2, 6-2 by the world No.1 Serena in the second round.

The Briton's victory over Venus Williams in the opening round was more evidence of her talent and she showed plenty of courage and class as she matched the American from the baseline.

Robson broke serve in the first game but Williams is a class apart just now and hit back straight away before pulling away to win the opening set.

Two good holds at the start of the second kept Robson alive but Williams broke for 4-2 and wrapped it up when the teenager double-faulted two games later.

Robson, who is still in the doubles here, will now rise to around 34 in the rankings and, if she does not get a seeded berth for this month's French Open, she seems sure to do so in time for Wimbledon.