DOHA, Qatar -- Rafael Nadal struggled past Philipp Kohlschreiber while defending Qatar Open champion Roger Federer routed Nikolay Davydenko in their season openers on Tuesday.

The second-ranked Nadal overcame Kohlschreiber of Germany 6-3, 6-7 (2), 6-3 in a match that lasted 2½ hours. Federer, who lost badly to Nadal and No. 1-ranked Novak Djokovic over the weekend at an exhibition tournament in Abu Dhabi, showed he had shaken off the rust by overwhelming the injury-plagued Davydenko 6-2, 6-2 in just 54 minutes.

Also, No. 6 Jo-Wilfried Tsonga beat Tunisian wild card Malek Jaziri 7-6 (5), 6-7 (5), 6-1 and fourth-ranked Gael Monfils defeated Rui Machado of Portugal 7-5, 6-3.

Nadal, who has struggled with a sore left shoulder since the end of last season, started well and looked headed for a routine victory. But the 43rd-ranked Kohlschreiber stepped up his net play in the second set and jumped to a 4-1 lead on his way to evening the match. Kohlschreiber went up a break in the third but Nadal broke back and took control from there.

Nadal ripped a cross-court forehand past Kohlschreiber to go up 2-1 and then broke for 3-1. Helped by an improving serve and able to win most of the big rallies, Nadal jumped to 5-2 and closed the match with an acrobatic overhead smash and then a vicious cross-court forehand that Kohlschreiber couldn't reach.

"In general, for me, (this) was a really positive match," Nadal said. "I think I played a very good first set. The only moment that I didn't play well was the beginning of the second and after the tiebreak. For the rest, I think I played a very solid match."

Nadal admitted Kohlschreiber was a tough opening draw, since he often plays much better than his ranking would indicate. Nadal, though, has never lost to Kohlschreiber in eight meetings.

In a rematch of last year's Qatar Open final, Federer expected a tricky encounter with Davydenko. But it was clear from the start that Davydenko -- a former world No. 3 who has fallen in the rankings to 41st -- would be no match for the third-ranked Swiss.

Federer jumped to early leads in both sets. He had his service game working and repeatedly pounced on Davydenko's weak serves.

Hoping for a fourth title in Doha, Federer was able to move the Russian around the court at will as he racked up 18 winners to Davydenko's seven. Davydenko also hurt himself with 20 unforced errors.

"It was a good first match for me into the new season and I think it was a combination between me playing actually really well and Nikolay just not finding his range, you know, what we're used to seeing from him in the past," Federer said. "But I take these victories any time, especially against a top player like him."

Federer said he was most happy he bounced back from his play in Abu Dhabi, where he served erratically and struggled to break his opponents.

"I thought my forehand and backhand was working. I think I had good variation on my serve which wasn't the case last week," he said. "So I'm happy I was able to pull myself together and make that happen. So things have obviously changed here and I'm happy the conditions suit me."

Tsonga was challenged almost from the start by Jaziri in their first meeting. The 118th-ranked Tunisian kept Tsonga off balance, mixing in volleys and drop shots that had the third seed cursing to himself. But Tsonga could rely on his serve, which produced 12 aces.

The match turned in Tsonga's favor in the deciding set when the Frenchman started going to the net more often.

"It was good for me to play a long time, to stay a long time on the court," Tsonga said. "But it was not easy, not easy today. Malek was in good shape. With the wind, it was really difficult to play my best tennis."