LONDON — Saying tennis is "potentially at a crossroads," an independent review panel found 45 matches that merit further investigation because of irregular betting patterns and offered a host of recommendations to the sport's leaders for combatting corruption.

The panel's 66-page report, prompted in part by suspicions surrounding a match last year involving fourth-ranked Nikolay Davydenko, was released Monday by the International Tennis Federation, the ATP, the WTA Tour and the four Grand Slams.

The 45 unidentified matches, played in the last five years, were among 73 examined by the panel, which warned of "inside information."

"We do not doubt that criminal elements may be involved in seeking to subvert or corrupt some players or players' support staff; that may even involve organized criminal gangs, but to elevate that suspicion to a claim of 'Mafia' involvement is, in our view, a distortion of the facts and is positively damaging to the sport," the report said.

The review was prompted by a series of events connected to gambling in tennis.

Most prominently, an online betting site, in an unprecedented move, voided all bets on a match involving Davydenko last year because of suspicious gambling patterns.

The site received about $7 million in wagers on the match, 10 times the usual amount, and most of the money backed 87th-ranked Martin Vassallo Arguello — with some coming in even after he lost the opening set. The match ended when Davydenko quit in the third set, citing a foot injury. An ATP inquiry is ongoing.

"The name 'Davydenko' is being abused," his manager, Ronnie Leitgeb, said Monday from Poertschach, Austria, where the Russian is playing. "If his name keeps coming up in rumors and nothing has been proven in the upcoming two or three months, we'll consider taking legal action."

Since that case was opened, other players have come forward to say they have been approached by people trying to influence a match. Belgian player Gilles Elseneer said he was offered — and turned down — more than $100,000 to lose a first-round match against Potito Starace of Italy at Wimbledon in 2005.

Five players, all Italians, have been fined and suspended for betting on tennis.

"Whilst professional tennis is neither institutionally nor systematically corrupt, it is potentially at a crossroads," the report said. "There is sufficient cause for concern about the integrity of some players and those outside tennis who seek to corrupt them."

The report comes a week before the start of the year's second Grand Slam tournament, the French Open. In February, that tournament's organizers filed suit in a bid to ban online gambling companies from offering bets on the Grand Slam tournament, but last month a Belgian court ruled in favor of the betting companies.

"I think the attempt of Roland Garros to avoid betting on their tournament was great," Leitgeb said. "That was the right way to try to avoid any damage to their event."

Besides noting the 45 matches to be investigated further, the review panel made 15 recommendations that the sport's four governing bodies accepted — including "any player caught cheating should be punished by a lengthy suspension for a first offense and, if the circumstances merit it, a life ban." They also agreed to have a uniform anti-corruption program and an integrity unit.

The report also examines the practice of "tanking," which it defines as "a player not giving 'best efforts' in a match." While no specific recommendations were made, the report did "urge officials to be alert to such activity and to deal with it as a break of the rules whenever such behavior can be proved."

Another of the recommendations allows only players and essential tournament personnel to have access to the locker rooms at tournaments. The report said many believe that insider knowledge, such as a player's injury or illness that is not widely known, gets passed on to bettors.

Michael Chang, the 1989 French Open champion, was pleased to hear about the report, saying in a telephone interview that "it's been sad to see" so much discussion about gambling in tennis over the past year.

"The organizations that are involved are just trying to keep everything in check, before something gets out of hand, where tennis is not the clean sport that it has been and that it should be," said Chang, who'll be inducted into the International Tennis Hall of Fame in July.