How did you rate Roger Federer's third-round performance [he beat Radek Stepanek in straight sets on Sunday] and how far is he away from top form?

After the slapdash performance against [Thiago] Alves in the previous round, Federer came on court today with real purpose and there was that aura about him. In the back of his mind I am sure was the fact that Stepanek was one of the nine players who has beaten him this year and while Roger does not like losing, he certainly does not like losing to the same person twice and remembers things like that. It was Federer at his best on what, it must be pointed out, was a very blustery day.

He had the bit between his teeth and if not quite at the absolute peak of his powers we are certainly starting to see the return of Roger.

Andy Roddick [who beat Andreas Seppi of Italy 6-2, 7-5, 7-6] was once touted as a serious rival to Federer and Nadal, yet has won just one grand slam tournament. How would you evaluate his career thus far?

Roddick was a little unlucky this year in that he picked up a shoulder and back injury in Rome that ruled him out of the French Open and when Wimbledon came around he was not quite right for that either. He has parted company with his coach, his brother, John Roddick, and Patrick McEnroe has joined his group and I think he feels that there is still business to be done. He won the US Open when he was very young [beating Juan Carlos Ferrero in 2003, aged just 21], which is every player's dream, to win their home grand-slam event.

On the one hand I think he feels fulfilled having accomplished that but on the other, frustrated. Just when it looked like he was going to take the world by storm along came Federer. All the strengths he had, Federer had them too, only better, vastly reducing Roddick's chances of winning at Wimbledon and the US Open, the tournaments which best suit his game. But I detect an eagerness about him here and you write him off at your peril.

Andy Murray was in majestic form in his first-round match, but since then has been increasingly erratic. Where is his game right now?

Andy makes his debut on [Court] Arthur Ashe tonight [against Stanislas Wawrinka] as the last match, after Serena [Williams]. It really will be an intense atmosphere out there in front of a big crowd on Labor Day [a US Bank Holiday], but I think he will handle it really well. He finds it hard to get himself up for the more mundane matches, but he was two points away from defeat against Jurgen Melzer and when it really mattered he produced the goods. Even though he is 3-0 against Wawrinka on hard courts this year [the Swiss beat him on clay in Rome] he cannot afford to be as lax as he was in round three. Having said all that, Murray in four [sets].

Readers who did not see the Olympics [where he won a gold medal in the doubles with Roger Federer] may not know much about Stanislas Wawrinka. What is he like as an opponent?

He has a super backhand, is a great athlete and has a good all-round game like Andy. He is solid, lacks a little consistency and has been with the same coach since he was eight years old, which certainly sets him apart from Murray. But I think both these players will look at this match as a great opportunity. If you would have said to them at the start of the tournament get through this round and you'll be facing either Kei Nishikori of Japan or Juan Martin Del Potro of Argentina for a place in the semi-finals they would certainly have taken it!

Neil Harman was talking to Richard Neale