Roger Federer and Justine Henin were the predictable heroes in what turned out to be one of the most unpredictable tennis seasons on record.

They swept all before them to once again rule the tennis world in 2007, winning five of the eight grand slams on offer between them, but their achievements were overshadowed by a multitude of plots that came to the fore.

The genteel sport of tennis has been left reeling over the past four months with allegations of match-fixing, gambling, doping and even poisoning hitting the headlines.

The scourge of corruption that has blighted sports such as soccer, cricket and horse-racing, surfaced in tennis.

A match between world No 4 Nikolay Davydenko and lowly ranked Argentine Martin Vassallo Arguello in Poland in August was voided by British online betting exchange Betfair because of unusual betting patterns, raising suspicions of match-fixing.

Russian Davydenko, who retired hurt from the match, denies any involvement.

But since then, a procession of male players, including Wimbledon doubles champion Michael Llodra, have said they were offered money to throw matches. All added they had rebuffed the offers.

For Davydenko, who usually struggles to get any global exposure or even a shirt sponsor despite his high ranking, being in the spotlight proved to be an uncomfortable experience.

"I am disappointed because I'm a top player and people are talking (about it) not only in Russia, in my country, (but) also talking everywhere in the world," he said.

Tennis great Billie Jean King said the threat of match-fixing was one of the pitfalls of modern sport.

"People follow the money in sports. In the '60s nobody cared because there wasn't any money," the American said.

The tennis bodies - the International Tennis Federation (ITF), the men's ATP and women's WTA governing associations and the four grand slam events - reacted quickly to the threat by joining forces to set up an 'integrity unit'.

Under the scheme, players have 48 hours to report any suspicious behaviour or risk sanctions.

While no player has so far been found guilty of corruption, little-known Italian Alessio Di Mauro became the first professional to be banned (for nine months) and fined US$60,000 ($80,558) for gambling in the sport.

Di Mauro escaped a more severe penalty as he was found to have bet only on other players' matches.

An incredulous Martina Hingis could not be bothered to hang around and see what punishment would be meted out to her after she was notified that she had failed a drugs test at Wimbledon.