Russia's Nikolay Davydenko saw off Argentine Juan Martin del Potro 6-3, 6-4 to win the season ending ATP World Tour Finals at the 02 in London. The 28 year old who had shocked world number

one and top seed Roger Federer in the semi-finals. Earlier in the round-robin stages, Davydenko defeated Rafa Nadal and Robin Soderling, losing his only match of the week to Novak Djokovic. It was his fifth time at the Championships and his second successive final.

Serena Williams defeated older sister Venus at the end of season Sony Ericsson Championships in Doha as she regained the world number one status back from Dinara Safina. It was the

second time Serena took the WTA title as she dominated from start to finish. It was Serena's fourth straight win over Venus as she now leads their head-to-head 13-10. Serena previously won the title in 2001 and it was her third title of the season after wins at the Australian Open and Wimbledon.