Phil Mickelson maintained a one-shot lead after two rounds of the US PGA Tour's Northern Trust Open, buoyed by a dramatic eagle from the fairway that helped offset some less impressive play.

"I probably didn't play the greatest today, but I was able to kind of salvage a good round," said Mickelson, who carded a one-under par 70 at Riviera Country Club for a six-under total of 136.

He was one shot in front of Pat Perez, whose six-under 65 matched the best round of the day and gave him sole possession of second place on five-under 137.

Australian Jarrod Lyle also carded a bogey-free 65 to lead a group sharing third place on four-under 138.

A handful of players failed to finish before darkness fell, but none figured on the leaderboard.

Mickelson, seeking to earn a second straight US tour title after a scintillating come-from-behind victory at Pebble Beach on Sunday, took a one-shot lead into the second round.

He struggled to build momentum, but got a big break at the 460-yard par-four eighth—his penultimate hole—where his L-wedge from 110 yards out found the hole.

Mickelson said he wasn't firing at the pin, but trying to "sidespin" the ball towards the hole.

"It kind of sidespun right in the hole, so it worked out just perfect," he said.