The winner will earn just over £900,000 and 1500 rankings points
Nadal has had a truly stellar season that has confirmed his place among the all-time greats of the sport, winning three of the four Grand Slam titles and
completing his personal clean sweep with a first US Open victory in September.
Roddick: 784 in 63 matches
Soderling: 713, 72
Federer: 626, 73
Berdych: 530, 65
Murray: 497, 60
Djokovic: 284, 68
Nadal: 288, 76
Ferrer: 237, 78
Indoor conditions are the toughest for the Mallorcan to handle and he has struggled physically in the closing weeks of years past, failing to win a set in his three matches in London last year.
He missed Paris last week as a precaution because of a shoulder injury,
but the end-of-season championship is now the biggest title missing from his CV and he is determined to make up for last year.
That makes him more motivated - and more dangerous - than ever, and whatever the conditions he is the man to beat now.
Federer has a superb record in this event - as in most others - with four previous victories and he is clearly a strong contender once again.
FIRST SERVE PERCENTAGE
The Swiss appeared to be as good as ever when
he won a record 16th Grand Slam title at the Australian Open in January
but his incredible run of 23 Grand Slam semis came to an end in the last eight at the French Open, before an even more surprising exit at the same stage of Wimbledon.
Recent back-to-back wins at smaller events in Stockholm and Basle suggest his form is coming back but the vulnerability was still there when he let five match points slip away in defeat by Gael Monfils last week.
Federer remains the second-best player in the world but his crown has slipped sufficiently that his rivals are no longer beaten before they hit a ball.
Djokovic appears to be back in the frame to challenge the top two next year after recovering from a mid-season slump to play quite brilliantly on his way to the US Open final.
POINTS WON ON 1ST SERVE (%)
Problems with his serve, illness and allergies have all contributed to patchy form at times but for all that his results have remained remarkably consistent, making the last eight or better at all the Slams and remaining in the world's top three all year.
next week's Davis Cup final against France
could prove a distraction as the proud Serb looks to lead his nation to their first ever title.
The new world number four has confirmed himself as a top-10 player in 2010 and followed up his stunning 2009 win over Nadal at the French Open
by beating Federer this year as he returned to the final,
only to lose to Nadal.
POINTS WON ON 2ND SERVE (%)
Soderling arrives in London on the back of winning his first Masters title in Paris last week, although that highlights the fact that the Swede struggles to convert his talent into titles - he has won just six in his career.
Still, he has always relished indoor conditions with his big, flat serve and heavy groundstrokes, and beating Nadal and Djokovic on his way to the semi-finals last year ensures that he will be considered a contender at the O2 once again.
Murray is fortunate that he will enjoy home support at the end-of-season finale during the peak years of his career - but the downside is that he must now carry the burden of a nation's hopes twice a year, rather than just during the Wimbledon bubble.
SERVICE GAMES WON (%)
His form is hard to judge as only last month he was brilliant in
beating Federer to win the Shanghai Masters,
but last week he made a disappointing exit to Monfils in Paris.
The year will be considered a disappointment as he remains without a Grand Slam title, but that is simply the result of expectations raised high by the level of his own performances.
If we see the Murray of Melbourne, Toronto or Shanghai, he will be a match for anyone. Playing great tennis is not a problem for the Scot, doing so on a consistent basis is.
Every year there is a player who limps over the finish line to qualify for London - this year it is Berdych. Touted as a potential Grand Slam winner and even world number one in his teenage years, the 25-year-old Czech will end the year inside the world's top 10 for the first time.
BREAK POINTS SAVED (%)
That is thanks to a superb summer during which he reached his first Grand Slam semi-final at Roland Garros, only to surpass that
at Wimbledon a few weeks later as he beat Federer on his way to reaching the final.
Nadal proved far too strong on the final Sunday in SW19, however, and since then Berdych has lost form alarmingly.
Two match wins in his last five tournaments left his London place in danger, but with a big game and no pressure he could yet play a significant role, if only by ruining someone else's hopes.
When a player is described as a "wall" it might not seem especially flattering, but in Ferrer's case it refers to his most admirable qualities.
BREAK POINTS CONVERTED (%)
The Spanish number two is almost as relentless as the Spanish number one in his ability to pound the baseline, and the 28-year-old is experienced enough to know that the occasional foray to the net will be essential.
His rivals will certainly not underestimate him. On his only previous appearance in the Finals in 2007, Ferrer beat Nadal, Djokovic and Roddick before losing to Federer in the final.
His five-set defeat by Fernando Verdasco at the US Open
was one of the matches of 2010 and, while he may not be the biggest draw for spectators in London, Ferrer's competitve spirit is likely to provide drama somewhere along the line.
There would have been relief all round among sponsors, ticket vendors, TV executives and the written press when Roddick sealed his place at the O2 in Paris last week - but none would have been more delighted than the American himself after he missed out on London's spectacular debut last year through injury.
RETURN GAMES WON (%)
There have been more physical issues this year but he did enough in the closing weeks of the season to qualify for a mightily impressive eighth consecutive year.
Nine straight years in the top 10 prove the 28-year-old has learned how to work the advantages of a huge serve and big forehand, and manage relative weaknesses in the forecourt and on the backhand.
If he can find the form of Miami
and Indian Wells in March, he could still do some damage.
By Piers Newbery and David Ornstein
Stats courtesy of
ATP World Tour