R2 LEADERBOARD US unless stated -14 JJ Henry -10 JB Holmes -9 S Lowery, P Stankowski Selected others: -8 M Calcavecchia, D Toms -7 P Mickelson -3 J Rose (GB), B Davis (GB)

The American is likely to carry a four-shot lead into the third round after his 10-under round of 61, one shot off the Scottsdale course record.

"It was one of those days. The hole looked big," he said of his birdie run, which started at the par-four ninth.

"I hit a lot of good shots and my speed was really good today on the greens."

Henry's closest challenger is compatriot JB Holmes, who finished the day with a bogey to fall back to 10 under.

To finish at five is really disappointing - I was thinking I could get to nine or 10 Phil Mickelson

Three-times champion Mark Calcavecchia stayed in contention two shots further back, alongside Sony Open winner David Toms.

And Phil Mickelson had a five-under round of 66 to move up to seven under for the tournament.

"It wasn't a frustrating day, I played great," said the left-hander, who attended university at Arizona State.

"I was seven under through 12 holes and I really had it going. To finish at five is really disappointing. I was thinking I could get to nine or 10."

Englishmen Justin Rose and Brian Davis had matching 68s to end on five under overall.