Deep field stands in the way of Federer's quest for a Masters Cup three-peat

The ATP season will culminate in Shanghai at the prestigious Masters Cup. After a year of plenty of highs and a bevy of lows, the top eight players (excluding Rafael Nadal, who withdrew) are seeking to end the year on a high note.

Roger Federer, again, leads the pack. Far removed from a disappointing first half of the season, the Swiss maestro found redemption at the U.S. Open. But whether he can carry that momentum for the duration of the Masters Cup remains the overarching question.

Here's a breakdown of the field.

Roger Federer

Seed: 1
2008 record: 65-13, four titles
2008 Grand Slams: SF Australian Open, F French Open, F Wimbledon, W U.S. Open
Career Grand Slam titles: 13
Previous appearances at year-end championships: 2002-07

Federer's year started off on the wrong foot as he fought to recover from an offseason bout with mononucleosis. It became an uphill battle for the Swiss master, and he never fully rebounded to his usual high standards.

Frustration was the name of the game for him until August when things began to look up, but by then he had surrendered the No. 1 ranking for the first time since February 2004.

Initially hoping for a much-sought-after gold medal in singles at the Beijing Games -- a quest that ended in the quarterfinals -- Federer credits picking up the doubles gold medal with countryman Stanislas Wawrinka for turning his year around. He saved his season by winning his first Grand Slam title of 2008 -- a fifth successive U.S. Open title. He now sits only one Grand Slam title away from equaling Pete Sampras' record of 14.

If Federer can capture his third career Tennis Masters Cup trophy in Shanghai, it will leave this incredible competitor on the upswing as he looks ahead to 2009.

Novak Djokovic

Seed: 2
2008 record: 60-16, three titles
2008 Grand Slams: W, SF, 2R, SF
Career Grand Slam titles: one
Previous appearance at year-end championships: 2007

Djokovic joined the elite Grand Slam champion club when he won the Australian Open in January, losing only one set in the final during the two-week major. He also played to form by living up to his No. 3 seeding at the Beijing Games, taking home the bronze medal in his first Olympic appearance.

He won three of six finals and briefly had a chance to move into the No. 2 ranking spot, an opportunity that went by the wayside. But he looks likely to finish the season as No. 3 for the second year in a row.

The knock on Djokovic this year is that his competitive nature has turned him into a rather pugnacious guy who doesn't always grasp the concept of being cooperative. Up until this year, he showed a playful side in his imitations of fellow players -- some of the subjects, however, did not approve of his spot-on mimicking.

Djokovic's given all that jovial stuff up, and the serious side doesn't come across quite as charming. Some pundits wonder whether the task of upending Rafael Nadal and Federer is beyond his ability and making him anxious.

But his results for the year certainly indicate this baseline basher has the goods to remain one of the toughest players on tour to beat.

Andy Murray

Seed: 3
2008 record: 55-15, five titles
2008 Grand Slams: 1R, 3R, QF, F
Career Grand Slam titles: none
Previous appearance at year-end championships: none

Murray came close to fulfilling the dreams of the British public by reaching his first Grand Slam final. Unfortunately for Murray, he ran into a more accomplished and determined Roger Federer at the U.S. Open.

Despite the loss, it magnified a successful season for Murray, who has a career-high five titles in 2008, including successive Masters Series championships in Cincinnati and Madrid. He became the first British citizen to win three titles in a season since Mark Cox in 1975.

The British public, which keeps close tabs on Murray's whereabouts and results, are holding their breath that he holds form and finishes in the top four, which would make him the first Scot to secure such a ranking since its inception 36 years ago.

A hard-court fan, Murray has an explosive game backed by a big serve. However, at times a bristly personality overshadows his talent. His temper seems to act as a safeguard, though, enabling him to handle the weighty expectations.

Nikolay Davydenko

Seed: 4
2008 record: 53-19, three titles
2008 Grand Slams: 4R, 3R, 1R, 4R
Career Grand Slam titles: none
Previous appearance at year-end championships: 2005-07

Some might think if they asked Davydenko what the highlight of his year was, he would say being cleared of any implication regarding the infamous match-fixing investigation from the Sopot tournament during the summer of 2007.

But Davydenko handled that uncomfortable situation with great aplomb during the year the ATP investigated the match. Therefore, it's more likely Davydenko would say picking up his second career Masters Series victory at the Sony Ericsson Open in Miami was his most significant moment of 2008.

A steady-as-you-go, mild-mannered player, Davydenko seems to fly under the radar most of the time. His methodical work ethic seems to work -- he will conclude 2008 with a fourth consecutive top-10 finish.

Davydenko won three of four final appearances in 2008, which accounts for an impressive 14-4 record in career finals. He has won at least one title every year since 2003.

The one downside to his season was not reaching a quarterfinal showing at a Grand Slam for the first time since 2004, so he'll be hoping for a solid result in Shanghai.

Andy Roddick

Seed: 5
2008 record: 49-17
2008 Grand Slams: 3R, DNP, 2R, QF
Career Grand Slam titles: one
Previous appearance at year-end championships: 2003, '04, '06, '07

For the first time since 2002, Roddick failed to reach at least one Grand Slam semifinal during a season. But the gritty and determined Roddick fought valiantly all season long, guaranteeing his fifth outing at the Tennis Masters Cup.

Roddick is still a consistent force in the game -- he journeyed to at least the quarterfinals in 11 of 15 tournaments he played this year -- and with trophies in San Jose, Dubai and Beijing, he has won at least one title each year since 2001.

In flux with no coach on record at the moment, Roddick should view 2008 as a success story. It was highlighted by defeating Roger Federer in Miami at the Sony Ericsson Open -- just his second win over the dominant Swiss in 17 matches played.

Roddick reached the semifinal round at the Tennis Masters Cup three previous times, including last year, so he'll be putting a lot of pressure on himself to hang around deep into the week.

Jo-Wilfried Tsonga

Seed: 6
2008 record: 33-12, two titles
2008 Grand Slams: F, DNP, DNP, 3R
Career Grand Slam titles: none
Previous appearance at year-end championships: none

Finding a path to a top-50 year-end finish in 2007 for the first time in his career, Jo-Wilfried Tsonga exploded on the scene during the first couple of months this year. It wasn't so noticeable that he cruised to the semifinals of the Adelaide tournament in January, but what he did next captured international attention.

Showing personality and fortitude, Tsonga scalped three top-10 players en route to his first career Grand Slam final at the Australian Open, which included wins over Andy Murray in the first round, fellow Frenchman Richard Gasquet in the fourth and then world No. 2 Rafael Nadal in the semifinals.

It's not known how Tsonga would have performed the rest of the year after a bothersome right knee knocked him out of competition for lengthy periods. Instead of playing on his home turf at the French Open, he underwent arthroscopic surgery and subsequently missed Wimbledon, before returning to the tour at the U.S. Open.

Tsonga proved his knee is fully mended when he took out defending Paris champion David Nalbandian in three sets to win his second title of the year last week.

Juan Martin Del Potro

Seed: 7
2008 record: 45-13, four titles
2008 Grand Slams: 2R, 2R, 2R, QF
Career Grand Slam titles: none
Previous appearance at year-end championships: none

After a back injury in the spring, the talented Argentinean started to realize his potential. He came alive after Wimbledon, winning four consecutive titles in five final appearances, which eventually led to his top-10 breakthrough in October. Del Potro showed proficiency on all surfaces, winning Stuttgart and Kitzbuhel on clay, followed by Los Angeles and Washington on hard courts.

Del Potro's summer success gave way to his first Grand Slam quarterfinal appearance at the U.S. Open.

Like Tsonga, he ended the 2007 season with a top-50 finish for the first time. Also along with Tsonga, Del Potro is a top candidate for 2008 Most Improved Player of the Year honors. His stock rose when he helped Argentina reach the upcoming Davis Cup final against Spain, which will take place on his home soil later this month.

Gilles Simon

Seed: 8
2008 record: 49-25, three titles
2008 Grand Slams: 3R, 1R, 3R, 3R
Career Grand Slam titles: none
Previous appearance at year-end championships: none

Gilles Simon has probably already shipped off a thank-you present to world No. 1 Rafael Nadal. The Spaniard's decision to rest his sore right knee for the Davis Cup final paved the way for the Frenchman to earn his first berth in the year-end extravaganza.

Simon's standout season includes victories over the top three players in the game. He defeated then-world No. 1 Roger Federer at Masters Series Canada en route to a semifinal showing. He defeated Nadal, after the Spaniard took over as No. 1, with a semifinal victory at Masters Series Madrid last month and earlier in the year, just weeks after Novak Djokovic won the Australian Open, Simon upended the Serbian in the round of 16 at Marseille.

A Frenchman with a preference for hard courts, Simon now owns five career titles, including three this year at Casablanca, Indianapolis and Bucharest.

Knowing he's capable of beating the best players in the world is bound to give Simon a bit of confidence in this elite grouping. But escaping from the round-robin portion of the competition might be a stretch.

Sandra Harwitt is a freelance tennis writer for ESPN.com.