Lance Armstrong. Alex Rodriguez. Kory Friesen.

Kory who?

Flouting rules for performance-enhancing drugs has felled some of the biggest names in sports. Now that list could include competitive video game players like Mr. Friesen, after he boasted that he, his teammates and other professional gamers took prescription drugs to help them focus in a competition.

In response to those comments, the Electronic Sports League, one of the most successful leagues in competitive video gaming, said on Wednesday that it would test players for performance-enhancing drugs starting at a tournament in August. E.S.L. said it would work with two international agencies — the same ones that help oversee anti-doping policies for cycling, the Olympics and other sports — to create anti-doping guidelines and a testing program for players.

The announcement is perhaps the clearest sign yet that e-sports, as professional gaming is widely known, is evolving into a mainstream form of competitive entertainment. This year, overall revenue from the global e-sports business is expected to surpass $250 million from more than 113 million e-sports fans worldwide, according to estimates from Newzoo, a games research firm.

But the growing stakes for players — prize money is expected to reach $71 million — is creating new temptations.