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WIMBLEDON, England -- Six-time champion Roger Federer overcame a two-set deficit to avert a monumental first-round upset at Wimbledon, beating Alejandro Falla 5-7, 4-6, 6-4, 7-6 (1), 6-0 on Monday.

Federer has reached the tournament final each of the past seven years, but he barely survived the traditional opening match on Centre Court as defending champion.

"I live another day," Federer said. "This one is one I should have lost. That's sometimes how grass-court tennis works."

Falla, ranked 60th, had lost all 11 sets in his previous four matches against Federer, but the Colombian played brilliant tennis to take charge of the match early. The turnaround came in the fourth set with Falla serving for the match and three points from victory, when Federer broke for only the second time.

He played his best tennis of the day after that. It's the third time in a row he has won after losing the first two sets at a Grand Slam event, but the close call was a new experience in such an early round.

"You definitely feel uncomfortable," Federer said. "For me, it's not normal to be down two sets to love. Especially at Wimbledon and early on in Grand Slams, it's something I'm not quite used to."

After winning the first two sets, Falla received treatment from a trainer during the next three changeovers for an upper left leg injury but he said it didn't affect the outcome. But it was only when he served for the biggest victory of his career at 5-4 in the fourth set that his game unraveled

Falla made shaky errors on the first two points, and a pair of deft forehands by Federer gave him the break. The Swiss ran away with the tiebreaker, taking advantage of four more unforced errors by Falla, and the disconsolate Colombian mustered little resistance in the final set.

"I think about the lost opportunity," Falla said. "On the other hand, I played a great match. I had Federer against the ropes."

No. 7-seeded Nikolay Davydenko also overcame a two-set deficit, along with Kevin Anderson's 36 aces, and won 3-6, 6-7 (4), 7-6 (3), 7-5, 9-7.

No. 5 Andy Roddick, who lost to Federer in last year's epic final, began his title bid by beating fellow American Rajeev Ram 6-3, 6-2, 6-2. Roddick never faced a break point and committed only 10 unforced errors.

In women's play, five-time champion Venus Williams beat Rossana de los Rios 6-3, 6-2. Williams hit 31 winners to four for de los Rios.

"It's definitely good to be back," said Williams, seeded second behind her sister Serena, the defending champion. "I love playing on the grass."

Grand Slam champions Kim Clijsters and Justine Henin began Wimbledon comebacks with victories. Clijsters won easily in her first match at the All England Club since 2006, beating Maria Elena Camerin 6-0, 6-3. Henin, playing at Wimbledon for the first time since 2007, defeated Anastasija Sevastova 6-4, 6-3.

French Open champion Francesca Schiavone lost to Vera Dushevina, 6-7 (0), 7-5, 6-1 in nearly three hours. The No. 5-seeded Schiavone committed 38 unforced errors and fell to 0-2 since the improbable run to her first Grand Slam title.

Among the men, No. 11 Marin Cilic lost to Florian Mayer 6-2, 6-4, 7-6 (1), and No. 17 Ivan Ljubicic was beaten by Michal Przysiezny 7-5, 7-6 (5), 6-3. French Open semifinalist Tomas Berdych advanced, as did No. 16 Jurgen Melzer, No. 21 Gael Monfils and Americans Mardy Fish and Brendan Evans.

Dustin Brown, the first Jamaican man to play in a Grand Slam tournament since 1974, lost to Melzer 6-3, 4-6, 6-2, 6-3.

The first day's play began in warm sunshine and ended with the Centre Court roof closed at twilight to allow the completion of No. 3 Novak Djokovic's victory over Olivier Rochus, 4-6, 6-2, 3-6, 6-4, 6-2. The match ended at 11 p.m local time.

There had been signs coming into the tournament that Federer might be vulnerable. He lost at the French Open this month in the quarterfinals, his earliest Grand Slam exit in six years. Then he dropped to No. 2 in the rankings behind nemesis Rafael Nadal. Then at a Wimbledon warm-up event came Federer's second grass-court defeat since 2003, extending his drought of nearly five months without a title.

But no one expected so much trouble against a 26-year-old journeyman who has yet to win a tournament. There were stretches of stunned silence from the crowd, dumbfounded by the score. Fans also roared in appreciation of Falla's frequent winners.

"He played great," Federer said. "He was the one who put me in that kind of a score. I thought I was actually playing decent. Credit to him."

The match was Falla's third in the past four weeks against Federer, which at first worked to the Colombian's advantage. "It shouldn't have," Federer said, before cracking a smile. "He should have known that I was going to beat him. But he forgot I beat him."

The left-handed Falla was unfazed by Federer's serve, one of the sport's best, and repeatedly won points serving to Federer's backhand -- a tactic frequently employed by another lefty, Nadal.

Federer searched for more than two hours to find his championship form. He slipped several times on the immaculate lawn and shanked shots, hitting one forehand so wild that Falla had to leap out of the way.

Trouble for Federer began at 5-all in the first set. He had the first double-fault of the match on the opening point, then hit a poor volley and lost the next point. Falla dropped a backhand volley onto the baseline for a winner for the first service break, then served out the set.

Falla broke again for a 4-3 lead in the second set, then served out the set in a long, tense game.

Federer was 0-for-6 on break-point chances before putting a forehand winner on the line to close out the third set. He lost serve to start the next set, though, and found himself on the verge of defeat with Falla serving at 5-4.

Then Federer's big surge began. Barely 30 minutes later, he kissed the line with his final shot for a winner and walked to the net to give Falla a sympathetic pat on the shoulder.

Clijsters has been sidelined since late April with a left foot injury, but showed plenty of spring in her step playing the opening match on Court 2.

Seeded eighth, the Belgian dominated from the baseline and with her return. She never faced a break point and won 12 of 15 points on Camerin's second serve.

Clijsters ended a 2 1/2-year retirement last August and won the U.S. Open in September.