WIMBLEDON, England -- Marathon man John Isner faded at the finish of another five-setter at Wimbledon.
The highest-ranked American failed to convert a match point in the fourth set and lost in the first round to Alejandro Falla of Colombia, 6-4, 6-7 (7), 3-6, 7-6 (7), 7-5 on Monday.
Isner is best known for winning the longest match in tennis history two years ago in the first round at the All England Club, when he edged Nicolas Mahut 70-68 in the fifth set. Isner also went five sets in the second round at the French Open last month, losing 18-16 to Paul-Henri Mathieu. He has been eliminated in five sets in each of the past three Grand Slams.
Since climbing to a career-best No. 9 in the rankings in mid-April, Isner has gone 3-5.
"I'm just really down on myself right now," he said. "I'm trying not to feel the outside pressure. There are some good things expected of me, and I'm glad I'm in that position, but I'm just not performing right now. It's just ugly right now."
The 6-foot-9 Isner hit 31 aces and said he has been pleased with his serve, but not the rest of his game.
"Sometimes, and lately it has been happening quite a lot, I get out there in the match and I'm just so clouded," he said. "I just can't seem to figure things out. I'm my own worst enemy out there. It's all mental for me, and it's pretty poor on my part."
Isner held a match point with Falla serving at 6-7 in the fourth set. The Colombian was on the ropes again serving at 5-all in the final set when he faced three break points, but Isner failed to convert them, then lost serve in the final game.
"I didn't put my opponent away," Isner said. "I had my chances, and I didn't do it. It's all on me."
American men went 3-3 on the first day of the tournament. Ryan Harrison won and will next face top-ranked Novak Djokovic, the defending champion. Michael Russell and Ryan Sweeting also advanced, while James Blake and Donald Young lost.
Djokovic beat former No. 1 Juan Carlos Ferrero 6-3, 6-3, 6-1.
In keeping with custom, the defending men's champ played the first match Monday on Centre Court. Djokovic was broken in his second service game but held the rest of the way, losing only nine points on his first serve. He had 13 aces.
"Can happen like this, 'cause you are not in the rhythm of the match, starting the tournament," Ferrero observed later. "Today, I take the break very early. But he [broke] me again, very fast."
The top-ranked Djokovic is bidding for his sixth Grand Slam title. He won three in a row before losing the French Open final to Rafael Nadal two weeks ago.
The only defending men's champion to lose a first-round match at Wimbledon in the Open era was Lleyton Hewitt in 2003.
With Djokovic on Centre Court, Roger Federer had a familiar result on an unfamiliar court in the first round.
The Swiss six-time champion was assigned to play his opening game on Court 1 instead of Centre Court at the All England Club for the first time since 2003, but he was his usual dominant self in beating Albert Ramos 6-1, 6-1, 6-1 on Monday.
Federer declined to interpret the court assignment as a slight.
"I expected it," he said. "I figured if I won, they would have to put me on Centre Court. That's how I tried to understand the situation. I don't mind it. You want to get to Centre Court. If you make it down the stretch, you will get your Centre Court matches. But it was as nice on Court 1 today."
Federer broke Ramos eight times while losing his serve once in the first set.
"Maybe he isn't the most experienced grass-court player out there, that's for sure," Federer said. "I was able to take advantage of it and play a very clean match. It's always nice to save energy, and it gives you confidence as well to close out matches easily. Things worked out perfectly."
The 16-time Grand Slam champion is looking to equal the record of seven Wimbledon titles held by Pete Sampras and William Renshaw.
The sixth-seeded Czech was looking to reach the second round for the eighth straight year but lost 7-6 (5), 7-6 (4), 7-6 (4) on Centre Court.
Berdych lost to Nadal in the final in 2010 after beating Federer in the quarterfinals. He struggled to counter Gulbis' serve on Monday, though, with the Latvian hitting 30 aces.
Both players were broken once in the second set -- with Berdych converting the only break point he earned in the match -- but Gulbis proved stronger in every tiebreaker.
David Nalbandian lost his first match since being disqualified for injuring a line judge by kicking an advertisement board against his shin during the Queen's Club final.
The Argentine was outplayed by eighth-seeded Janko Tipsarevic in the opening round. Nalbandian controlled his emotions Monday, but the Serb still beat him 6-4, 7-6 (4), 6-2.
Nalbandian, the 2002 Wimbledon finalist, said he felt good support from the crowd despite the incident at Queen's, and that "I think everybody understood [it] wasn't a good thing that I did, but was very unlucky as well."
Nalbandian was fined by the ATP and docked 150 ranking points for unsportsmanlike conduct.
Information from The Associated Press was used in this report.