Heather Watson admitted she was not firing on all cylinders after her first round defeat at this year’s Wimbledon Championships.

Watson, the British ladies number two, has not long returned to the circuit after a long lay-off with glandular fever, and her lack of match fitness showed in a straight sets defeat to US teenager Madison Keys, 6-3 7-5, this morning.

Having reached the third round last year, the 21-year-old world number 57 is now looking forward to returning to training full time.

She said: “I wasn't 100 per cent when I came back for the French Open in May, but I think I came back at the right time. I wanted matches. I wanted to do the fitness work and get the feeling back of playing matches.

“Today, I think I did not really find my game. I don't really feel like my reactions were there and I didn't feel fully 100 per cent confident in my game.

“That needs work, and that's normal with coming back and not having many matches.”

She added: “I don't feel quick and the same as I used to be, but I think also that's because I haven't done as much fitness work. 

“I haven't run, for example, because when I run too much, I get a sore foot.  We didn't want that to happen before this tournament.”

Despite her lethargy on the court, Watson praised her conqueror and predicted big things for the 18-year-old American.

“I saw Madison about a year ago, and I saw her play.  I thought, ‘This girl's got a good game, she's going to start climbing’.  She has.  She's climbed so quickly,” she said.

“Some outsiders might have look at my draw and thought ‘She hasn't got a seeded player, she's got a good draw’. 

“But I know Madison is a good player. She's going to be top 30 soon and maybe even higher.”

Watson’s defeat leaves only Laura Robson and Tara Moore flying the GB flag in the ladies singles – Robson faces Maria Kirilenko, while Moore, ranked 194 in the world, faces Kaia Kanepi of Estonia, ranked 46.