Each of the big four won a Grand Slam title in 2012, but Andy Murray additionally grabbed Olympic gold. If he wins the World Tour Finals, how can Murray not be considered the men's MVP?
Here's an analysis of both groups, accompanied by our fearless forecast.
Before the Paris Masters, Djokovic said he felt much fresher than at the same stage last year. Then he went out and lost to Sam Querrey.
"During the second set I already felt that physically I'm down," Djokovic told reporters.
His physical deterioration, from the middle of the second set onward, was easy to spot, and an illness to his father understandably weighed Djokovic down further. Yet we'd expect Djokovic to close out any opponent when leading by such a margin.
Djokovic, too, was fortunate not to lose to Murray in straight sets in Shanghai.
His form is patchy.
The pressure, to a large extent, is off Murray, and he knows it.
"I feel a little bit more relaxed this year than I have in previous years because I've managed to win the U.S. Open," Murray said.
Murray has lost three times since the U.S. Open, but all have come after holding match points. Don't call it a letdown. His on-court demeanor suggests the Scot wants to collect more majors.
Expect his concentration to be heightened this week. And should we expect more one-hour sets when Murray tangles with Djokovic?
Berdych loves the Davis Cup, and he'll lead the Czech Republic against Spain in the final on home soil less than a week after the World Tour Finals conclude.
In 2010, Djokovic was in the same position -- Serbia hosted France -- and reached the semifinals in London, only to produce an insipid performance against Federer. The Czech Republic, which hasn't won the Davis Cup since 1980 (when it was Czechoslovakia), won't be intimidated since Nadal isn't around, but Berdych can ill afford to be at less than 100 percent.
Berdych remains a threat to anyone in the field, but will he indeed be thinking of Prague?
Tsonga marched into the final last year and stole a set from Federer. But he entered the event playing well, appearing in the final at the Paris Masters, where Federer was there to stop him again.
This fall, Tsonga retired in Valencia and disappointed against David Ferrer in Paris, perhaps as a result of overloading his schedule -- London marks his sixth tournament in as many weeks. His recent record versus his Group A foes doesn't make for pleasant reading -- he has lost five in a row to Murray, six in a row to Djokovic and two in a row to Berdych.
As ever, though, Tsonga is sure to give us moments of brilliance.
Prediction: Murray, Djokovic to advance
For most of his career, Federer has been immune from off-court criticism. But recently, some have carved into the 17-time Grand Slam champion.
According to news stories emanating from his native Switzerland, Federer is demanding a substantial increase in appearance fees to continue showing up at his hometown tournament of Basel, and he asked Switzerland's tennis federation not to pick Basel as the site of a first-round Davis Cup series in 2013 because it puts too much pressure on him to play. On court, Federer lost his first indoor hard-court match in two years, when he was upset by Juan Martin del Potro in Basel.
Will Federer be adversely affected?
Federer rarely has trouble focusing when he is on court, and he owns a combined 18-0 record against Ferrer and Janko Tipsarevic. Federer lost to del Potro by the slimmest of margins -- a third-set tiebreaker in the Basel final.
What a season Ferrer is having. He advanced to at least the quarterfinals at all of the majors -- a first for him -- won at home in Valencia and bagged his maiden Masters title in Paris.
That Ferrer was the last man standing in Paris was more impressive given several of his fellow contestants in London checked out early. Yes, it made his task easier, but Ferrer could have joined the Eurostar traveling party and mailed it in, too, especially on Saturday when he met local darling Michael Llodra.
Any chance that Ferrer, Spain's No. 1 in the Davis Cup final, will be distracted? Less so than Berdych. He's mentally tougher and has already won the Davis Cup -- although he'd gladly take another title.
Juan Martin del Potro
The seven-match losing streak against Federer is over, part of a stretch in which del Potro won back-to-back indoor titles in Vienna and Basel. Llodra, fatigue and, you would imagine, wanting to get to London ended the Argentine's bid for three in a row.
His return to the year-end championships is a positive for the game, and barring more injuries, del Potro will be a regular at the World Tour Finals for a while.
Ferrer and del Potro figure to compete for second place in the group, and del Potro has lost seven sets in succession to Ferrer -- not winning more than four games in any of them.
Here is one thing we know: Tipsarevic won't retire because of illness, as he did against Jerzy Janowicz in Paris. Nerves might not be a factor, since Tipsarevic already made his debut at the year-end championships in 2011 when Murray withdrew. He proceeded to extend Berdych to three sets and downed a tired Djokovic.
Tipsarevic has never won a set against del Potro, but his matches against Federer at the Australian Open in 2008 and Ferrer two months ago at the U.S. Open prove he can mix with the best of them.
Prediction: Federer, Ferrer to advance.
Semifinals: Murray defeats Ferrer; Federer defeats Djokovic