London, England -- (Sports Network) - Scotland's Andy Murray thrilled the British crowd with a three-set victory over U.S. Open champ Juan Martin del Potro to open the season-ending ATP World Finals.

Murray notched a 6-3, 3-6, 6-2 victory in the first round-robin match of Group A. The other Group A match Sunday will pit French Open and Wimbledon champ Roger Federer against Fernando Verdasco.

The first five games of the opening match went to Murray, but he stumbled in the second set and del Potro was able to open a 3-0 lead on the way to forcing a decisive third. Murray, though, broke in the second game of the final set en route to a 4-1 lead and cruised to the finish.

Group B play starts Monday in the exclusive eight-man field. Australian Open champ Rafael Nadal will meet French Open runner-up Robin Soderling in one of the day's matches, while Novak Djokovic and Nikolay Davydenko will square off in the other.

Federer will try to finish as the year-end No. 1 for the fifth time in six years, while Nadal has a shot to capture the honor for a second straight season.