Roger Federer has asked fans for patience as he prepares to step up his comeback from injury this month.
Federer has missed a year of tennis after requiring two operations to correct a long-standing knee problem.
He has stepped it up in practice recently, with Dominic Stephan Stricker and Dan Evans providing the professional hitting partners, but he says he will be taking things slowly upon his return.
"It was very important to me that I could play points and sets for the last two months," Federer told the press in Doha.
"First Stricker came to Dubai and most recently I played about 20 sets with Dan Evans. I am very happy with my knee.
"The knee will dictate what my comeback looks like. It sure is rare to see a 40 year old back on tour after so much time.
"It is important that I am free of pain. I'm curious to see how it plays out.
"The opponent will feel it if you are not at a 100 per cent. I feel that I am on a good level. But not in top form yet.
"When I wake up in the morning I feel pretty good. The pain is under control.
“I'm not sure my knee will hold up, but I'm confident, otherwise I wouldn't be here.
“If I can pull off a couple of matches here in Doha, I'll be happy. The expectations are very low. I hope I can surprise myself."
Despite the positive progress, Federer says he actually hasn't scheduled anything in until after Wimbledon at this point.
With the Olympics, US Open, and Laver Cup due to take place after that, though, it is likely those dates will be added to once he assess how his knee is holding up to playing again.
“I have to take it match by match," he said. "First Doha, then decide about Dubai.
"After Dubai there is a fitness unit of four to six weeks. I hope then I'll be even more explosive.
"For the time being I'm only planning until Wimbledon.
"I hope I will be 100% by Wimbledon, and then the season start. Perhaps I surprise myself, like I did in practice for the last three weeks."
For more exclusive content from Tennisbuzz, including news, features, trivia, promotions and more, please be sure to sign up for our newsletter below or via our home page.
Why not test your tennis knowledge by tackling one of our fiendish quizzes too?