"(Tiger has) been the man in golf for the last 15 years, and it's great for golf to have him play well, " McIlroy said.

CNN: McIlroy happy to be chasing Tiger

He has emerged as Rivera's heir apparent, and Rivera himself noted Robertson's importance after he saw his setup man driving off on a golf cart with his foot immobilized.

WSJ: Yankee Reliever David Robertson Injured in Fall

In another twist, fellow American Bo Van Pelt had shot a 59 in the pro-am Wednesday, but it does not count for the record books, while Mickelson himself carded a 59 at the PGA Grand Slam of Golf in 2004, a four-man invitational tournament which does not count towards the official money list.

CNN: STORY HIGHLIGHTS