Miami - Roger Federer is feeling the natural frustration of a tennis hero whose last title came just shy of six months ago.

The usually solid Swiss smashed his racket at a moment of third-set tension as he went down to a 3-6, 6-2, 6-3 semi-final loss to Novak Djokovic at the Miami Masters. He last lifted a trophy at his home Swiss Open in Basel on October 20.

Federer, who lost his Australian Open trophy to Rafael Nadal this season, is feeling his former dominance slip.

"There's not a lot of pressure on me," said the 13-time Grand Slam champion who also stands one title away from levelling on the all-time best of Pete Sampras. "I haven't been winning twenty tournaments in a row, so nobody expects me to win really.

"It's been a tough last year or so, especially in the hardcourts. My game never really clicked except for the US Open where I thought I played great."

Federer has battled various setbacks including a case of 2008 glandular fever and a recurring back problem, which he tried to cure with rest after Melbourne.

"I think when I was finding my form again, the back problem hit me. It was unfortunate, you know, but thank God the hardcourt season is over," said the winner of 49 hardcourt matches in one of his glory years, 2006.

Federer, who has lost the last three French Open finals to Nadal, is scheduled to play on clay only in Rome and Madrid before Roland Garros, with his opening date on the surface nearly a full month away in last April in the Eternal City.

"I'm moving over to clay, a new chapter," said the Swiss.

But amid his despair of his game, Federer still was able to defend his unusual racket smash.

"I didn't lose it (his temper), I was just frustrated. Just because I smashed the racket doesn't mean I lost it. It didn't feel great but it's just a natural thing I did." (dpa)