As the Olympic Games get under way in London, officials there say concerns over doping have been replaced by fears of “match-fixing” and “betting.”

Sports betting is big in London. Illegal bookmaking in Asia and the Internet has also expanded the reach of sports betting. Coming soon: several states, including New Jersey, in the U.S. are pushing to legalize sports betting.

The boom in sports betting is likely to increase pressure on athletes to fix games. Indeed, there have been a number of sports betting scandals over the years as this list here shows.