David Ferrer delighted with victory over Juan Martin del Potro

David Ferrer has expressed his delight at defeating Juan Martin del Potro at the ATP World Tour Finals on Tuesday.

The 30-year-old got the better of his Argentine opponent 6-3 3-6 6-4 at the O2 Arena in London to begin his Group B campaign on a winning note.

"I am very, very, very happy," the Spaniard is quoted as saying by the BBC. "It was a top match, and it was very difficult to play against Juan Martin. I hope the people in here enjoyed our tennis.

"I don't know the secret [of my good form]. It has been the best season of my career. Maybe it's because I didn't have a big injury."

Ferrer will take on Roger Federer on Thursday.