Roger Federer is able to joke about his shock Wimbledon defeat last year but the seven-time champion is deadly serious about his title ambitions 12 months on.

Wacky Wednesday saw plenty of upsets but none bigger than defending champion Federer losing to Sergiy Stakhovsky, ending the Swiss star's run of 36 straight grand slam quarter-finals.

Last year was one of the most difficult of Federer's career, with back problems dogging him for much of the season.

He won only one title, the pre-Wimbledon event in Halle, and the 32-year-old arrived in London having again won the German grass-court event.

But there the similarities end, with Federer confident he is in a much better position to challenge for an eighth Wimbledon trophy.

He said of the impact of last year's loss: "T hat was done a week after Wimbledon. It was just one of the big goals I set for myself. I failed. Back to work. Get yourself in shape.

"I'm happy that here I am in a much better place than I was last year. I also did come from winning Halle but I think it maybe masked the problems I was playing with, the way I was playing.

"I see him (Stakhovsky) and we always joke about the match and all that stuff, that we can only face each other in the final this year, so it's all good for both of us - well for me at least.

"I'm totally at peace. I can accept these defeats, even though they were not fun in any way. But they're part of a tennis player's life.

"This year I feel all the options are there. Return, serve, serve and volley, my backhand - everything is working to my liking. For that reason, I feel I'm a bit more relaxed mentally.

"I clearly want to do better than last year, there's no doubt about it."

Having gone nine years without losing before the last eight at a grand slam, Federer has made the quarter-finals just once in his last four major tournaments.

That came at the Australian Open, when he beat Andy Murray before losing to Rafael Nadal, but at the French Open he was again the victim of an upset when Ernests Gulbis knocked him out in the fourth round.

Wimbledon has been Federer's most successful slam, and many pundits feel it remains his best chance to win an 18th title.

The fourth seed said: " I feel like if things click here, I should be able to win the tournament, whereas at the French I feel like I'm slightly more dependent on Rafa. He's the only guy really.

"But that doesn't mean I don't believe I can win the French, it's just that I know he's been so dominant over there that it goes through him regardless.

"I feel like if I play my game it's more on my racquet (at Wimbledon). As soon as that's the case, you're more confident in your chances. I feel I have a very good chance again this year."

Federer's only grand slam title in the last four years came at the All England Club in 2012, when he defeated Andy Murray in the final.

The British number one finally got his hands on the trophy 12 months ago and will look to emulate Fred Perry once again by successfully defending it.

It has been a tough 12 months for Murray, who spent the first part of the season trying to hit top form again after back surgery.

Federer has been impressed by his response, saying: " I think he's fought back nicely, bravely. I think he is where he wants to be before Wimbledon.

"Clearly in a perfect world you don't want to have surgery. I think he's good enough now to defend again, whereas maybe three, four, five months ago, honestly I wasn't sure about that.

"But now I think the way he's playing, the way he's got himself back into shape again, I think he can really believe again. That's what's most important now.

"Being defending champion is never an easy thing. But he played so well on grass the last few years. I would feel comfortable if I was Andy at this point."