Defending champion Keegan Bradley will be the fourth contestant in the PGA Grand Slam of Golf at Port Royal Golf Course in October.The PGA announced today that Bradley was selected to take part in the annual event in Bermuda after PGA champion Rory McIlroy bowed out due to a prior commitment.Bradley will defend his 2011 title against Masters champion Bubba Watson, US Open champion Webb Simpson and The Open winner Ernie Els.This is the first time Watson and Simpson are taking part in the Grand Slam.Els, who also competed last year, is returning for the fourth time, having won in 1997 and 2010.Bradley ground out a level-par 71 to finish on four-under-par and held off a determined final round charge from Charl Schwartzel to win last year’s PGA Grand Slam by one shot.The 26-year-old, who was named last year’s Rookie of the Year, has won three tour events, most notably the 2011 PGA Championship.He is one of three golfers to win on their major debut, along with Ben Curtis and Francis Ouimet.McIlroy had committed to compete in the BMW Masters, October 25-28, in Shanghai, China, prior to last month’s victory in the PGA Championship. The new event was added to the European Tour schedule in April.The PGA Grand Slam of Golf, which takes place at Port Royal from October 22 to 24, features the most difficult qualification requirement in the game a major championship.Televised by TNT, the event features a $1.35 million purse, with the winner receiving $600,000, second place $300,000, third place $250,000 and fourth place $200,000.