There are moments in every Masters when the momentum shifts inexorably in favor of the winner, moments when the avalanche cuts loose and you just know that you're watching an inexorable march toward victory. Jack Nicklaus's tee shot on 16 in 1986, Gene Sarazen's double-eagle on 15 in 1935, Tiger Woods' chip on 16 in 2005, Phil Mickelson's astonishing shot from the pine straw on 13 in 2010 -- each of these was a tipping point, an instant when you knew you were watching a winning round in progress.
[Related: Complete Masters leaderboard]
Saturday afternoon, as the sun dipped below the pines, Rory McIlroy might just have added another to the long list of legendary Masters shots. On the fringe at No. 17, 30 feet away from the cup, McIlroy rolled in a putt that would have curved around the corner of a building. Just like that, he was up four strokes on the field, and finished the day at -12.
This wasn't supposed to happen. McIlroy was supposed to falter today, or even fall completely apart, youth and inexperience crumbling in the face of Masters history. Instead, McIlroy extended his lead, and nobody could mount enough of a charge to close the gap.
You want a sign that there's a generational shift afoot in golf? Here it is: when McIlroy's putt rolled in on 17, the cheering was so loud that Tiger Woods had to step away from his second shot just ahead on 18. How many times in his career had Woods done that to others?
Had this putt happened on a Sunday, it would have joined the ranks of the immortal shots at Augusta ... assuming McIlroy wins, of course. Even so, it'll be one for the highlight reels if the 21-year-old kid manages to bring home the green jacket.
Leading a Masters on a Saturday evening, even by four strokes, doesn't mean you'll be anywhere close on Sunday evening. But it's a fine start.