Its first player is said to have been Louis X, king of France in the 1300s. King Henry VIII played it off indoor walls three centuries later. Today, names like Federer, Sampras, Graf, Williams, Ashe and King ring with legendary status.

We know tennis as a sport governed by clear rules and detailed etiquette, including wearing only white when playing at Wimbledon. Perhaps it’s this backdrop of sophistication and implied ethics that makes recent allegations of cheating so hard to believe.

In January, just as crowds descended on the Australian Open – the first in the four “Grand Slam” series of tournaments – the BBC and Buzzfeed broke a scandalous story. They reported that a core group of 16 of the world’s top 50 professional tennis players allegedly have engaged in “match fixing,” intentionally throwing games and matches in exchange for illegal bribes from gambling syndicates in Russia, Italy and northern Sicily.

Just as disconcerting, The Guardian published a story earlier this month claiming that some tennis referees and umpires intentionally delayed reporting critical calls and match updates in order to allow bettors more time to clean up on the day’s wagers.

Here’s how Vanity Fair explains it:

Speculation aside, two things are clear: tennis is a magnet for gambling, and because of the nature of the game and its lopsided economic structure, it is also exceedingly vulnerable to match-fixing. Bettors adore tennis: it is played year-round, there are scores of matches each week, it is a statistical feast, and there are all sorts of ways to wager on the sport. You can also bet on the results of individual sets, and whether a match will have any tiebreaks. You can even bet on whether the total games played in a set will be even or odd (honestly—there is a market for that). Much of the betting is online and high speed. Gambling agencies are even known to dispatch employees to tournaments so that they can instantaneously transmit data about matches, a practice known as courtsiding. According to the International Business Times, British bookmakers report that tennis is now second in popularity among bettors only to soccer, with billions of dollars being wagered on the sport each year. (William Hill, the big bookmaker, is a sponsor of the Australian.)

Sports gambling is hardly new. We put money down on football, baseball, golf – even the color of the horseracing jockey’s silks. It should come as no surprise that clay courts facilitate big bets as well as hard serves.

But this scandal whispers of the darker side of gambling. The greed unleashed by those on the sidelines can corrupt and infect, making losers of everyone — including the champions of the game.