Ben Affleck has been asked to stop playing blackjack in a Las Vegas casino during his recent visit to the Sin City, media reports said, citing sources.

Affleck was in Las Vegas on a “romantic getaway” with his wife, actress Jennifer Garner, at the Hard Rock Hotel & Casino, when security caught the actor was caught him counting cards. Casinos frown upon the technique, as it gives the practitioner a better chance of winning.

“Ben was banned from playing blackjack, not booted from the casino, because as the security said, ‘You are too good at the game,” a source told FOX411. “The hotel staff was really nice. They told him he could play other games and ended up getting him and Jennifer a car back to their hotel.”

Counting cards is not considered illegal unless a device is involved or signs or signals are used between players, James Taylor of the Nevada Gaming Control Board told E! News. "Just having a brilliant mind counting cards is fine," he said.

The venue had cause to be concerned: In 2001, Affleck won $800,000 playing blackjack there.