Stockholm - Roger Federer says he will rest as required to complete an exhausting 2008 season, while still feeling strong enough to test himself starting on Wednesday at the Madrid Masters.

The Swiss said Monday his self-imposed pause from the game which lasted for less than a month had been temporarily broken after he felt his strength and desire returning while taking time off in Dubai in recent days.

But it's a necessary short-term outlook for the 13-time Grand Slam champion, usually known as a master planner.

"I'll see where it takes me, I'm going week by week. I've felt no sickness," he said, in reference to his glandular fever episode of last winter which compromised his season.

"It was the tiredness, just everything together."

The number two withdrew from last week's Stockholm event won by David Nalbandian and said that the remainder of his 2008 schedule is subject to late decisions.

"Anything is possible, there are some exciting events left. And I have a chance to make more points," said the US Open champion whose title in New York saved what had been a poor season by his own lofty standards.

"I got my start in the indoor season (Milan title in 2001). It's not one that I like to miss. I love the game and I love to complete, that's why I'm back on the tour again."

Federer said even his home Basel event next week is on the line, depending on how he feels. He is then scheduled to play the Paris Masters, Shanghai Masters Cup in November along with a few exhibitions in Asia in mid-November.

Federer last competed as he helped Switzerland back into the World Group in Davis Cup in September. "The season was long and I felt very tired, I needed some rest."

But now that he's returned, Federer is all business as he heads into a Wednesday night opening in the second round against Czech Radek Stepanek.

"I'm feeling good enough now to win this event, so I came here and will play," said the 2006 Madrid champion and 2007 finalist against Nalbandian.

With all seeds handed first-round byes, the rest of the pack continued play on Monday after a Sunday start.

Gilles Simon of France, winner of three titles this season, put out Russian Igor Andreev 4-6, 6-1, 7-6 (9-7) while American Mardy Fish played for the first time since the US Open, taking a victory against Belgian Steve Darcis 6-1, 6-4.

Italy's Simone Bolelli, given a place when Moscow finalist Marat Safin pulled with a sore shoulder, beat Spain's Nicolas Almagro 7-6 (7-4), 6-1.