HOYLAKE, England -- Among the perks for many Americans at Open Championships is the ability to place legal wagers on the competition.

Betting is a way of life in the United Kingdom, and various gambling establishments dot the landscape, including several within a few miles of this year's venue, Royal Liverpool.

Rory McIlroy is the favorite to win the Open -- but he won't be able to put money on those odds this week. Stuart Franklin/Getty Images

But players are being told such places are off-limits, at least for bets on this week's Open. In a move believed to be a first, R&A officials have required competitors to sign a waiver stating they will not place wagers on the championship, multiple players confirmed to ESPN.com.

"It's really no different than what we already have on the European Tour and PGA Tour, so it doesn't change anything," Graeme McDowell said. "Honestly I love to gamble ... just not on golf!"

Multuple players said it is the first time they've been asked to sign the waiver, but R&A's executive director of championships Johnnie-Cole Hamilton said it has been in place since the 2011 Open.

Added R&A CEO Peter Dawson: "I can say that this whole business of keeping sport clean in terms of betting is very high on the IOC's agenda at the moment, and something that we're following very closely because it's just a killer to sport to think that any outcomes might have been predetermined. And I really don't think that's applying in golf. But we have to be vigilant."

"It doesn't matter to me," Jason Day said. "I don't follow that stuff either way."

Both the PGA Tour and European Tour have policies that prohibit players from gambling on tournaments. But at the Open, that didn't necessarily stop them from doing so in the past.

"I was shocked when they handed me the sheet to sign," said one player, who wanted to remain anonymous.

Caddies apparently were not required to sign the waiver.

"I can still go make the bet," said one caddie, who declined to be named.

One player representative, who also did not want his name revealed, said: "There's probably ... at least 30 guys in violation [of the no-bet waiver] already, and that number will be bigger by Thursday."

Local betting establishment William Hill lists Rory McIlroy as the tournament favorite at 12-1 odds. Tiger Woods and defending champion Phil Mickelson are both at 16-1 odds.

An array of possible bets exist, and each bookmaker has different variations and odds. In addition to betting on players to win, bets can be made on whether they will finish among the top five or top six. Shops offer odds on various things such as if a player will make a cut, how many bunkers he might find, etc. Odds are also given on the matchups in various groups.

Lee Trevino famously bet on himself before winning the 1971 Open Championship, placing 100 pounds at 14-1 odds. Over the years, he has maintained the story got embellished, saying a number of people he stayed with that week at Royal Birkdale also bet on him, especially after his odds rose following the first round.