It doesn't involve Tiger Woods, whose only rivals seem to be retired.
No, this is about the duel going on between Phil Mickelson and Vijay Singh, who are linked by victories and majors, and lately by losing. At stake is who will be regarded as the second-best player of his generation on the PGA Tour.
Mickelson lost in a sudden-death playoff in the FBR Open to J.B. Holmes, at the time No. 197 in the world. One week later, Singh looked like a lock to win the AT&T Pebble Beach National Pro-Am until a playoff loss to Steve Lowery, who checked in at No. 305 in the world.
"I let this one slip away," Singh said.
That's something they rarely do.
Mickelson is second among active players with 32 victories, one of them while he was still an amateur at Arizona State. Singh is right behind with 31 victories, the majority after he turned 40, and one more will put him atop the career list of foreign-born players.
Woods has 62 victories and is closer to Sam Snead's record 82 than anyone behind him. Even so, Mickelson and Singh are so far ahead of everyone else that next among active players is 43-year-old Davis Love III with 19 wins.
Both have won three majors -- Mickelson has two Masters and a PGA, Singh one Masters and two PGAs. Singh has won 13 times with Woods in the field, Mickelson has done that 11 times.
The biggest difference in their record is that Singh can look back on his career one day and say he was No. 1 in the world. He reached the top in 2004 when he won nine times and captured the money title for the second season in a row, and was a runaway winner as PGA Tour Player of the Year.
Mickelson has never been No. 1, and the closest he came to winning a money title was in 1996, Woods' last year as an amateur. He is only 37 and still has time, although his prospects look bleak when Woods is winning 30 percent of the time.
As rivals, Mickelson and Singh are anything but friends.
There was that confrontation in the Champions locker room at the Masters in 2005 when Singh complained Mickelson's metal spikes were too long. Twice last year when they played together in the PGA Tour Playoffs, Singh wore dark sunglasses that had ear plugs attached to them.
Ultimately, though, they will be judged by their PGA Tour records in the race to be second-best to Woods. Mickelson is slightly ahead at the moment, but his best golf might still be ahead of him.