Roger Federer hopes to be "100 per cent" fit in time for Wimbledon as he prepares to make his comeback in Doha this week.

Federer, who has needed two operations to correct a long-standing knee issue, is due to play in the Qatar Open this week.

The 39-year-old Swiss, with 20 Grand Slam titles to his name, told a press conference on Sunday: "I'm very happy to be back playing a tournament again. It's been a long time. I never thought it would take this long."

Federer, who is a three-time champion in Doha but has not competed there since 2012, will face either British number one and sometime practice partner Dan Evans or Frenchman Jeremy Chardy in his first match.

"I just feel like the story is not over. It's not like there's one particular reason that I wanted to keep playing tennis other than I enjoyed playing tennis, I enjoy being on the road.

"I'm still a work in progress but probably one of the other reasons for coming back is I want to get that high again of playing against the biggest players and in the biggest tournaments and hopefully winning them again.

"Hopefully I can play in front of crowds again."