The ATP World Tour Finals 2013 group stages continue play Tuesday as four other contenders and the top three players in the world start their campaign in the final ATP tournament of the season at the O2 in London.

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Rafael Nadal has one mission in this tournament and that is to protect his lead as world number one over nearest competitor Novak Djokovic, who is at number two. If the Spaniard can advance to the semifinal round in this tournament, he is assured of locking down the world number one ranking at the end of the semifinal season.

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Djokovic’s hope of landing in the top spot is out of his hands but he needs to win the tournament to have a chance at toppling down Nadal. The Serbian takes on rival Roger Federer in his World Tour Final opener while Nadal faces compatriot David Ferrer in his first match.

Nadal has 12,030 points to Djokovic's 10,610 entering the tournament in London.

Nadal has dominated Ferrer in 25 meetings winning 20 of those matches. However, one of the Ferrer-wins came last Saturday in the semifinals of the ATP World Tour Masters Paris when he won in straight sets, 6-3, 7-5.

Meanwhile, the Federer and Djokovic match-up continues one of the colorful rivalries in the history of the sport. The Swiss legend leads the all-time head-to-head match-up, 16-14 but the Serbian has won the last two and five of the last 7 matches.

The ATP World Tour Finals has a round-robin format which means that each player is assured of at least three matches. The players take on their group-mates once and the top two players in each group advance to the knockout semifinal round.

Ferrer and Nadal are grouped with Tomas Berdych of Czech Republic and Stanislas Wawrinka of Switzerland in Group A while Federer and Djokovic are in Group B with Juan Martin Del Potro of Argentina and Richard Gasguet of France.

Wawrinka and Del Potro drew first blood on opening day beating Berdych (6-3, 6-7 (0), 6-3) and Gasquet (6-7 (4), 6-3, 7-5), respectively.

2013 ATP World Tour Finals Round Robin Live Streaming and Schedule

Nov. 5, 2013 - All times in Australian Eastern Standard Time (AEST)

1:00 a.m. midnight – Rafael Nadal (Spain) vs. David Ferrer (Spain)
7:00 a.m. Roger Federer (Switzerland) vs. Novak Djokovic (Serbia)

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