The truth is, it probably is over. Probably.
With Bill Haas alone in third place and six behind Stenson, it would take a round similar to the one Phil shot on Thursday (8-under 63) to overtake the top spot. Let's go ahead and concede that as being highly unlikely, but take a deeper look at the options.
Haas has 14 birdies in three rounds (5, 4, 5). He probably won't shoot a 63, but a 4-under 67 isn't completely out of the question. Something like five birdies and one bogey or six birdies and two bogeys.
That, hypothetically, puts Haas at 10-under.
Stenson's 68 on Saturday was tied for the best round of the day. If we've learned anything over the years, it is that a low round is hard to follow. While 68 isn't ultra-low, it's still the round of the day. Stenson's also never won a major championship, and is sleeping on the 54-hole lead in a major for the first time. You're telling me that it isn't possible that he comes out tomorrow with the pressure on and fires a 3-over 74, dropping him to 9-under?
And then there's Phil. DID NOBODY WATCH WINGED FOOT IN 2006? It wasn't van de Veldian, but it demonstrates that Phil can blow it. For those that like trends, Phil started red hot, but has been worse every day following. You can't count out the possibility that Phil throws up a 73, with a bogey on the last hole, to miss a playoff by a shot.
The most dangerous thing for the Stenson / Mickelson duo is to lull themselves into a match-play nap. A Bill Haas or Andrew Johnston, in the group immediately ahead, quietly shoots 2- or 3-under on the front, but still hang about three back. Suddenly Haas or Johnston bags an eagle on 16 and an unlikely birdie on 17 or 18, and then Mickelson / Stenson wake up a bit too late to realize they just lost the lead with a hole or two to play.
Do I think Mickelson or Stenson will hoist the Claret Jug on Sunday? Yep. I'd say to the tune of about 80% certainty.
Now, raise your hand if you thought Jordan Spieth had sealed the deal on his second green jacket when he stepped on the 10th tee at Augusta National on a Sunday afternoon in April. Rae's Creek happened, just like pot bunkers at the Postage Stamp can happen. Tee balls can be lost in gorse bushes.
The fat lady is in the auditorium doing her warm ups, but she's a long way from taking the stage!