Say you like to gamble and know a thing or two about tennis. It’s Sunday, July 29, 2007, and the newcomer to your poker game, the guy who just guzzled all your beer and took you and your friends for several hundred dollars, offers you a can’t-miss, double-or-nothing bet: Pick either Nikolay Davydenko, the no. 4 ranked player in the world who is in a bit of a slump, to win two rounds at a clay tournament in Sopot, Poland, a title he won last year, or pick John Isner, a 6-foot-9-inch 22-year-old out of Georgia University playing his second ATP tournament, to beat Tim Henman in the first round of the Legg Mason Classic in Washington, D.C.

It’s a testament to how strange — and potentially scandalous — a week it was in tennis that this obvious scenario would have cost you a whole lot of dough. Isner fired 120 mph second-serves and won five consecutive third-set tiebreakers (what were the odds on that?) on his way to the Legg Mason final, where Andy Roddick took the starch out of him, 6–4, 7–6(4). Davydenko, the 26-year-old Russian, retired against Martin Vassallo Arguello in the second round in Sopot and now finds himself at the center of gambling allegations.

If there is anything to L’Affaire Davydenko, it would be most unwelcome news for tennis, which has been free of serious off-court troubles since 15-year-old Sesil Karatantcheva tested positive for steroids in 2005.

Here is a brief rundown of the facts. Davydenko won his firstround match in Sopot, a small tournament with a total of $500,000 in prize money. Yet Betfair, a British online gambling company, said it received $7 million in wages — 10 times what it might expect — on Davydenko’s second match. Most of the money favored Arguello, ranked no. 87. More concerning, bets for Arguello kept coming in after Davydenko won the first set, 6–2.

Arguello won the second set 6–3 and Davydenko retired in the third set after receiving treatment on his left foot. He then flew to Germany for more treatment in preparation for this week’s Masters tournament in Montreal. Arguello lost his next match to Albert Montanes, ranked no. 51.

Betfair voided all bets on the match and alerted the ATP Tour, whose chairman, Etienne de Villiers, has promised an independent investigation. Davydenko’s agent, Eckhard Oehms, denied that his client, or anyone associated with him, had any role in the incident. He told the Associate Press that Davydenko was “flabbergasted” when he learned of the inquiry.

At this point, we must take Davydenko at his word. Logic favors him, too: The no. 4 player in the world — a man whose steady game has won him more than $6 million and led him to two French Open semifinals (including this year) — would have to be rather stupid to risk his reputation by throwing a match.

But it’s not implausible, either. A player in Davydenko’s position — and I emphasize “player” rather than “Davydenko,” as I know nothing of his character that arouses suspicion — might very well be tempted to take this chance. Here are four reasons:

1) He has little fear of being caught or punished. Tennis officials have suspected gambling in the past and have yet to penalize or suspend anyone for it. In 2003, betting was suspended on a match in Lyon, France, between Yevgeny Kafelnikov, the former world no. 1, and Fernando Vicente, who had dropped 12 straight matches, after a large bet was placed on Vicente (who won in straight sets). Last year, Betfair alerted the tour to unusual bets during Wimbledon, when Britain’s Richard Bloomfield defeated the much-higher ranked Carlos Berlocq. Nothing came of either investigation.

2) A player like Davydenko might rightfully think himself underpaid compared with his peers. For tennis stars, prize money makes up a smaller component of yearly income than marketing deals and endorsements. Davydenko is among those pros who play tennis a lot better than they pump their fists or deliver pitches for watches and credit cards.

3) An early-round defeat wouldn’t seem too unusual. After winning three rounds at Wimbledon, his best ever performance at the All England Club, Davydenko lost three straight first-round matches to players ranked outside the top 50 (though one of them, Gael Monfils, is far more dangerous than his ranking suggests). His foot injury has not been a secret, either. Serious gamblers would know this.

4) Losing this match wouldn’t hurt his ranking. Davydenko’s agent told the AP that Davydenko couldn’t afford to lose this early in Sopot because he hadn’t won a tournament all year and wouldn’t be able to make up the points he would lose by failing to defend his title. But by the end of the year, the 175 points he dropped in Sopot likely won’t affect his ranking. Davydenko and Roddick are essentially tied for fourth in the rankings, but Davydenko has fewer points to defend in the weeks leading up to the U.S. Open. At last year’s Masters events in Toronto and Cincinnati, he lost in the second round. He can gain a lot of points with better performances this year, not to mention that the next closest men in the rankings — Fernando Gonzalez, Tommy Robredo, and Richard Gasquet — trail well behind. Yes, Davydenko has to defend his trip to the U.S. Open semifinals last year, but Roddick has to defend a trip to the final. It’s hard to imagine that he won’t qualify for the year-end Masters Cup. Perhaps this all has a simple explanation, like word of a worsening injury getting into the wrong hands via some scofflaw trainer who overheard a conversation in the locker room. But if you look at this case as a prosecutor or an outside investigator might, you’d think there was a lot of digging to do. Tour rules allow for a $100,000 fine and a permanent ban on tour events for involvement in gambling. So far Davydenko doesn’t even deserve a slap on the wrist; no one knows if he’s done anything. If he has, he ought to be finished.