MARANA, Ariz -- Shane Lowry became the first No. 64 seed to advance into the round of 16, but that is where it ended for the Irishman.
Lowry, who upset world No. 1 Rory McIlroy in the first round, ran into a red-hot Graeme McDowell on Saturday morning -- McDowell reeled off five birdies on the front nine to quickly seize the match.
Lowry took the early lead with a 10-footer for birdie at the par-5 second. But he gave that edge back -- and then some --with bogeys at the next two holes, and then McDowell went to work.
The Northern Irishman won the fifth, seventh and ninth holes with birdies to go 4 up at the turn. The two halved the next five holes with four pars and a birdie and even after a rare McDowell mistake at No. 15 it was just a matter of time.
"With the possibility of another 18 holes this afternoon, I was very keen to get the match out of the way as soon as I could, especially when I was 3 and 4 up," McDowell said.
"But Shane is a gritty competitor, very difficult to get the poker face on and really knuckle down and play Shane, being a good friend like he is. When he hit that pin with the flop shot on 13, I was licking my chops there thinking I had a chance to go 5 up with five to play, and all of a sudden I found myself down 16 and really not wanting to go down much past that."
SCORECARD STATS: McDowell made six birdies, nine pars and a bogey. Lowry had three birdies, 11 pars and two bogeys.
HOLES WON: McDowell won five holes. Lowry won two holes.
NEXT UP: McDowell plays Jason Day, who beat Bubba Watson 4 and 3.