Reuters
Russia's Nikolay Davydenko.

LONDON (AP):

Tennis officials are investigating suspicious betting patterns on a match involving top-seeded Nikolay Davydenko of Russia, who retired with an injury against a low-ranked opponent at an ATP tournament in Poland.

In an unprecedented move, British online gambling company Betfair voided all bets yesterday placed on Thursday's second-round match at the Prokom Open in Sopot between the defending champion and No. 4-ranked Davydenko and No. 87-ranked Martin Vassallo Arguello of Argentina.

Betfair said it received about US$7 million in bets on the match - 10 times the usual amount - and most of the money was on Arguello to win, even after Davydenko won the first set 6-2.

Arguello won the second set 6-3 and was leading 2-1 in the third when the Russian retired.

Davydenko said he aggravated a left foot injury in the second set. He received medical attention from a tournament trainer before deciding to quit.

Playing with injury

"I don't think that he (Davydenko) has something to do with this," Arguello said yesterday. "I was playing against him, but he was playing also with an injury and that's all that I know about the match, and that's also what I felt in the match. I felt nothing else."

Betfair, which has had an agreement with the ATP since 2003 to share information on any irregular betting activity, said it was concerned with the volume of wagers coming in on Arguello from the start.

"We think the market quite clearly wasn't fair," Betfair managing director Mark Davies said. "The prices seemed very odd. As a result, in the interest of fairness and integrity and in consultation with the ATP, we have decided to void the market and return all stakes to (bettors)."

It's the first time the company has taken such a step in any sport. Davies said Betfair would turn over its betting records for the ATP to investigate.