From The Death of Golf Department:

Phil Mickelson had two drivers in his bag last week, one that hits fades and one that hits draws.

From the Daily Telegraph:

In what could lead to an expensive trend among amateurs, Phil Mickelson, who won last week's BellSouth by a resounding 13 shots, will have two drivers in the bag when he plays in the Masters this week.

It is not, as was lightly suggested, a case of the player having got himself entangled in a ménage à trois with two different club-makers.

He is a Callaway man and the clubs in question are two FT3s - a 46in model, which he uses for a draw, and a 45in version, which he calls upon for fade.

The weights in the two clubs are distributed in such a way that he can use precisely the same swing for both.

Though there was the feeling that Mickelson was merely experimenting with the two clubs as he won last week's BellSouth by 13 shots from Jose Maria Olazabal and Zach Johnson, that was not the case. He was at Augusta the week before and made plans, then, as to which driver he would be using from which tee.