PACIFIC PALISADES (AFP/REUTERS) - World No. 1 Jordan Spieth bounced back from the worst opening round of his career on Friday but it wasn't enough to vault him into the weekend at the Northern Trust Open.

The Masters and US Open champion was 11 shots better in round two with a three-under par 68 but still missed the cut in the PGA Tour event.

The 22-year-old Texan missed his first cut since last year's Deutsche Bank Championship in Boston and his third cut in his past 20 worldwide starts.

Spieth said Friday that sloppy iron play and not enough time practicing on the driving range was his downfall at Riviera Country Club. He was hoping to use the event as an early stepping stone ahead of defending the Masters title in April at Augusta National.

He had shot shot a disappointing eight-over 79 on Thursday, leaving him 12 shots back of third-ranked Rory McIlroy, who shot 67.

"I guess Rory is considering this as the start to his run at the Masters," Spieth said of the first Major of the season that begins April 7. "This was not my start to the run at the Masters. Mine will start the next time."

Spieth plans to take next week off and then compete at the World Golf Championships Cadillac Championship at Donald trump's Doral course in Florida.

Dustin Johnson took advantage of good scoring conditions at a sun-splashed Riviera Country Club, firing a five-under 66 for an eight-under total of 134. That left the 31-year-old American level with compatriot Troy Merritt (66), and a stroke in front of Australia's Marc Leishman who carded a 67. Americans Kyle Reifers (68) and Justin Leonard (69), and Australian Adam Scott (68), were at six under.

McIlroy, among the late starters, shot a 69 to enter the weekend four shots back.