Nadal seals World No.1 spot by beating Wawrinka in ATP World Tour Finals

World number one Rafael Nadal has reportedly guaranteed that he will finish 2013 on top of the world rankings with a 7-6 (7/5), 7-6 (8/6) victory over Stanislas Wawrinka at the ATP World Tour Finals on Wednesday.

The Spaniard achieved that aim with a dominant victory over the Swiss seventh seed 24 hours after opening the tournament with a straight-sets win over David Ferrer.

According to Sport24, it is the third time that Nadal has finished a calendar year in pole position in the rankings, and the first since 2010, and he is the first player to end a year at number one three years after his last season-ending top spot.

Nadal's straight-sets victory over Wawrinka also booked his place in the semi-finals of the Tour Finals, with one group match against Tomas Berdych yet to come, with the report adding that his return to the top is a remarkable achievement given his seven-month-long period out from the field with severe knee tendonitis.

Thanking his team for his victory, Nadal hailed Wawrinka, saying that he played well, although he added that he is happy to be through to the semi-finals in the last tournament of the year and seal his No.1 ranking.

Since his return from injury, Nadal has won the French and US Open titles, as well as eight other tournaments, the report added.