The long-awaited dream finale

LONDON -- Rafael Nadal pulled off the improbable at last year's Australian Open. Battling more than five hours against Fernando Verdasco in one of the most bruising encounters in tournament history, he returned less than two days later to beat Roger Federer in a five-set classic. Clearly, downing Federer in arguably the greatest match of all time at Wimbledon in 2008 wasn't enough.

Nadal's powers of recovery will be tested yet again as he prepares to meet Federer in Sunday's dream finale at the biggest event he's never won, the ATP World Tour Finals.

Year-end championships coverage

" Scintillating London semifinals

" Rafa-Djoker rivalry picking up steam

" Roddick running out of time

" Masterful Fed dominates Murray

" Nadal snaps out of slump with style

" Maradona impressed with Djokovic

"I hope we can live up to expectations and really play a great match against each other again," Federer told reporters.

A victory for Nadal would cap an outstanding season that has seen the 24-year-old win three straight Grand Slam titles, lifting his total to nine, and becoming the dominant world No. 1. Federer took the first major at the Australian Open to boost his tally to 16 and needs a win to begin to overturn a 7-14 record against the Spanish lefty. Tennis fans have waited patiently for the mouth-watering duel -- the only other time they faced off in 2010 was at the Madrid Masters in May.

Should Federer conquer Nadal, it sets things up nicely for the next Australian Open in January.

"If he wins, a lot about Australia gets pretty interesting," two-time Grand Slam finalist Todd Martin said in an interview. "It would be great for Melbourne and tennis if Fed walked away with the last trophy of the year. If he loses, I don't think he will let it bother him."

While a flawless Federer barely broke a sweat in disposing of the disappointing Novak Djokovic on Saturday at London's O2 Arena, Nadal toiled for 3 hours, 11 minutes against Andy Murray in one of the finest matches of 2010. Luckily for Nadal, schedule-makers gave him the afternoon session, with Federer's rout coming in the evening.

"I don't know what's going to happen," Nadal told reporters. "You can imagine, right now I am very tired. That's the truth."

It's not the first occasion Nadal confronts Federer in the wake of an exhausting affair. Nadal competed for more than four hours against Djokovic on his favored surface of clay in the 2009 semifinals of the Madrid Masters. The next day, Federer prevailed comfortably, 6-4, 6-4, his lone victory versus Nadal in their past seven meetings.

Similarly, in 2007 in Chennai, India, and at the beginning of the campaign, Nadal went toe to toe with mentor Carlos Moya for four hours in the semis prior to claiming a single game in the final.

Federer downplayed the fatigue factor.

"I don't think it's going to have much effect on him," Federer said. "He's been done for a few hours now. He might be tucked up in bed already while I'm still doing my press conference here. That's his advantage that he played early."

Both have gone 4-0 in London. Federer continues to implement co-coach Paul Annacone's aggressive tactics, ripping second serves against Djokovic, going for winners earlier in rallies, driving through backhand returns when given the opportunity and picking his spots in heading to the net. The 6-1, 6-4 result was his third straight win against Djokovic after squandering two match points in their U.S. Open semifinal.

Nadal has improved with every match, recovering from wobbles in the second and third sets to down a courageous Murray 7-6 (5), 3-6, 7-6 (6).

Whatever the outcome, Federer and Nadal appear well ahead of the chasing pack. Federer's twins, and father time, haven't cut into the 29-year-old's motivation.

"Federer is the one that is most keen to take a step toward Nadal," seven-time Grand Slam champion Mats Wilander said in an interview. "I think Fed is as good as ever, but he's just not winning [titles]."

That could change Sunday.