Shane Lowry is probably going to win the 2019 Open Championship at Royal Portrush. Following a 67-67-63 start, he reset the 54-hole scoring record at this event and leads by four over Tommy Fleetwood, six over J.B. Holmes and at least seven over everyone else.

It's difficult to blow leads that big. However, Lowry was actually the last one to do it. He led Andrew Landry and Dustin Johnson by four after three rounds at the 2016 U.S. Open at Oakmont before shooting 76 and losing by three to D.J.

So let's roll through the top of the leaderboard and rank the golfers with the best chance of catching Lowry on Sunday at Portrush starting with an Englishman whose filthy 66 on Saturday will be lost to time because Lowry clipped him by three in one of the great 63s in major history.

1. Tommy Fleetwood (trails by 4): Forget the fact that he's the only golfer within even four strokes of Lowry. Fleetwood has made just two bogeys on the entire week, and he has the kind of ball-striking bonafides that make you think, "I mean, if it blows just a little bit ..." It's not going to be simple, but you can kind of imagine Fleetwood shooting 68 and Lowry shooting 72 and the former getting him in a playoff. If Lowry goes more than 1 under, though? That's probably a wrap.

2. Brooks Koepka (trails by 7): The case for Koepka is that he hasn't made a putt, closed Saturday with a pair of birdies and won't waver no matter what's happening around him. A typhoon could blow in off the North Atlantic while the Queen of England is trying to land her chopper on the sixth tee box, and Koepka would simply stick his tee in the ground and hit a shot to 12 feet. He's hitting it just like he always does at majors. It's just that this week nothing is falling.

3. Justin Rose (trails by 7): He's an assassin, and I could see him shooting something special on Sunday. Him and Koepka are the only former major winners in the top seven.

4. J.B. Holmes (trails by 6): Beyond Fleetwood (closest), Koepka (most juice) and Rose (class ball-striking), it gets a little bleak. When I envision Holmes winning a major (which, I admit, is not often), I don't normally see him making up six strokes in the final round. He's leading the field in driving accuracy, though, and nearly leading it in greens hit in regulation. So if he stays the course there and Lowry completely collapses, it could happen (it's just not likely).

5. Rickie Fowler (trails by 8): It's actually a decent spot for him. I'd rather the deficit be four or five, but if he can post 65 or 66 without a ton of pressure and the leaders just fall off a cliff (might actually take them literally falling off one of the cliffs into the sea), then he could win the first ever Back Door Open Championship.

6. Jordan Spieth (trails by 9): We're starting to get into a silly range here. Even if he makes up all the ground on Lowry, he still also has to beat Koepka by four. Seems ... unlikely. But I always go back to that final round at the Masters in 2018. With Spieth, something special always seems to be lurking.

T7. Justin Thomas and Dustin Johnson (trail by 12 and 14): Didn't see that coming, did you? Here's the problem for guys like Lee Westwood (eighth back) as well as Danny Willett, Jon Rahm and Tony Finau (nine back): If you're wagering on weather, there isn't enough separation time-wise for them to make up ground. 

Any weather that would adversely affect Lowry and Fleetwood would also clip the guys teeing off right behind them as well. That's why Johnson, who tees off three hours before the leaders, slides into this spot. Thomas trails by 12 and tees off 100 minutes before the last pairing, which is a good spot but not as good as Johnson. If either shoots 65 and it gets Biblical right as they finish up, it's in play. 

D.J. would know. He was leading and up 11 on Daniel Berger and Tony Finau after two rounds at the U.S. Open last year and ended the day tied with them for first. It's a one-in-a-thousand play, but when the leader is up seven on all but two guys, it might actually be your best bet.