NEW YORK -- Bothered by pain in his back, ribs and cramping legs, Novak Djokovic was face-down beside the court in Arthur Ashe Stadium, getting massaged by a trainer.
Having dropped a set against defending champion Rafael Nadal, Djokovic's grip on the U.S. Open final appeared to be starting to slip away and, worse, his body was breaking down.
His confidence? That, more than any particular stroke, is what Djokovic credits with transforming him from a top player to a great one -- and it never wavered one bit Monday night.
Producing a nearly perfect performance to match his nearly perfect season, the No. 1-ranked Djokovic returned brilliantly, whipped winners from all angles and beat No. 2 Nadal 6-2, 6-4, 6-7 (3), 6-1 in a match chock-full of lengthy, mesmerizing points to earn the first U.S. Open championship of his career and third Grand Slam trophy of 2011.
"In big matches, the winner is decided by small margins, a couple points. I guess the winner is the one who believes in victory more," said Djokovic, who is 64-2 with 10 tournament titles.
"I guess it just clicked in my head. Through the last couple of years, I didn't change my game in any major way. ... But I'm hitting shots that maybe I wasn't hitting," he explained. "I'm going for it. I'm more aggressive."
It's sure working, particularly against the man he replaced atop the rankings, Nadal.
A year ago, it was Nadal who won three major titles, including a win over Djokovic in the final at Flushing Meadows. That defeat helped Djokovic realize he was being too passive at key moments on his sport's most important stages and set him on a path that's led to one of the greatest seasons in the history of men's tennis -- or any sport, for that matter.
"I've had an amazing year," Djokovic said, "and it keeps going."
Nadal led their head-to-head series 16-7 at the end of 2010. And since? Djokovic is 6-0 against Nadal this year, all in tournament finals -- three on hard courts, including Monday; two on clay; and one on grass at Wimbledon. Djokovic also won the Australian Open in January, and is only the sixth man in the 40-plus years of the Open era to win three major titles in a single season.
"Obviously I'm disappointed," Nadal said, "but you know what this guy is doing is unbelievable."
With a couple of months left, Djokovic can set his sights on the best win-loss record in the modern era: John McEnroe went 82-3 in 1984, although that only included two Grand Slam titles, because he lost in the French Open final and didn't enter the Australian Open. Roger Federer was 81-4 in 2005 with two majors, exiting twice in the semifinals. Rod Laver (1962, 1969) and Don Budge (1938) are the only men to win all four Grand Slam tournaments in a year.
The biggest change Nadal has noticed in Djokovic?
"He's confident enough in every moment to keep believing in one more ball, one more ball," Nadal said. "His forehand is not more painful than before. His backhand is not more painful than before. Serve's the same."
Of all of Djokovic's skills, the one that separated him the most Monday was his return. He repeatedly sent serves back at Nadal's feet, forcing errors or giving Djokovic control of the point. That helped Djokovic accumulate an astounding 26 break points and convert 11.
Consider this: When Nadal completed his career Grand Slam by winning last year's U.S. Open, he was broken a total of five times in seven matches. Another telling statistic: Four times Monday, Nadal broke Djokovic -- only to have Djokovic break right back in the next game.
That's exactly what happened in the third game of the second set, which lasted 17 minutes and featured a bit of everything: 22 points; eight deuces; six break points; a time violation warning against Nadal (Djokovic was admonished later in the set); complaints by both men that the glare from the stadium lights was bothersome; seven exchanges that lasted at least 10 strokes.
After a 28-shot point, Djokovic leaned over and put his hands on his knees, his chest heaving. Nadal was the one who faltered, though. He double-faulted to set up break point No. 6, then -- on a great defensive lob by Djokovic -- put an overhead into the net.
More remarkable than all those breaks of serve was the way Djokovic seemed to break the will of the reliably relentless and indefatigable Nadal. At the end of the first set, when Djokovic reeled off six games in a row, and at the end of the match, Nadal wasn't even chasing Djokovic's shots.
"It was a tough match," said Nadal, who owns 10 major titles. "Physical, mental, everything."
Yes, and Djokovic turned this U.S. Open final rematch into something of a mismatch.
He entered this year with one Grand Slam title, at the 2008 Australian Open. Djokovic attributes his surge to a variety of factors, including a vastly improved serve, better fitness -- owing, at least in part, to a gluten-free diet he doesn't like to discuss in any detail -- and, mostly, a seemingly endless reservoir of self-belief dating to December, when he led Serbia to its first Davis Cup title.
Djokovic began a 43-match winning streak there, a run that ended with a semifinal loss to Federer in the French Open semifinals. The only other blemish on Djokovic's 2011 record was a loss to Andy Murray in last month's Cincinnati Masters final, where Djokovic stopped playing while trailing, citing a painful shoulder.
That was the 24-year-old Serb's last match before heading to Flushing Meadows. His shoulder was fine in New York, clearly, and while he was treated by a trainer and took painkilling pills in the late going Monday -- which is why his serves slowed to the 90s mph in the fourth set -- he overcame it.
With both men playing fantastic, court-covering defense in a grueling contest that lasted 4 hours, 10 minutes, there were more than two dozen points that lasted at least 15 strokes.
Djokovic quickly turned things around after falling behind 2-0 in each of the first two sets.
Those were tiny deficits compared to what he dealt with in the semifinals Saturday: He lost the first two sets to Federer, then faced two match points at 5-3, 40-15, before smacking a cross-court return winner that sent him on the way to taking the last four games.
By backing up that victory on Monday, Djokovic became only the second man to defeat Federer and Nadal during the course of one Grand Slam tournament. Juan Martin del Potro did it en route to the 2009 U.S. Open title.
The only time Djokovic truly faltered at all in the final was in the crucible of the third set, when he showed signs of being bothered by his lower back. His level dipped, and Nadal made one last stand. Djokovic went up 3-2 only to get broken, then served for the match at 6-5 and was broken again when he made two unforced errors, the second at the end of a 21-stroke exchange.
"When I lost that third set, it wasn't fun," Djokovic said. "I knew I wasn't physically there."
But in the fourth set, Djokovic was in control from the start, breaking in the second game with a forehand winner, then cruising from there.
When Djokovic ended it with another forehand winner, he raised his arms, then tossed aside his racket and dropped to the court. He pulled off his shirt and threw it into the stands, then put on a dark hat with "FDNY" written on it -- a nod to Sunday's 10th anniversary of the Sept. 11, 2001, terrorist attacks, which both he and Nadal mentioned during the trophy ceremony.
The final -- delayed a day to Monday by rain for the fourth consecutive U.S. Open -- was marked by spectators calling out during points or as the players were in their service motions, and while that's perhaps to be expected in New York (as opposed to, say, the staid All England Club), Djokovic and Nadal were bothered by it, and the chair umpire repeatedly chastised the unruly crowd.
Once he adjusted to the conditions, Djokovic disguised shots well, rearing back and ripping big shots off both wings -- often right near lines, if not right on them. He wound up with 55 winners -- 23 more than Nadal -- and, all in all, put on a masterful display of as diverse a game as one can have. He excelled at everything -- serving, returning, volleying, groundstrokes and the sort of constant movement and retrieving with which Nadal usually frustrates opponents.
Mostly, he kept telling himself he could win.
"The bottom line is that that's the whole point -- to win Grand Slams -- because these are the tournaments most important and most valuable in our sport," Djokovic said. "Right now I feel drained emotionally and physically and mentally."
Then, motioning with his right hand at the silver chalice that forever will carry his engraved name, Djokovic added: "But I have this trophy here, and this is what I was fighting for."