LOS ANGELES (AP) -- Bae Sang-moon is off to another great start at the Northern Trust Open. The next step is a better finish.
Bae played bogey-free on another gorgeous day at Riviera for a 5-under 66, giving him a one-shot lead over Aaron Baddeley among the early starters. Baddeley, who won at Riviera three years ago, birdied his last four holes for a 65.
Dustin Johnson, who led after the opening round at 66, played in the afternoon.
Bae was at 9-under 133.
The 27-year-old South Korean was tied for the lead going into the weekend at Riviera last year. Bae struggled to a 76 in the third round and never got back into contention.
''It was really, really good experience, and I learned a lot,'' Bae said. ''I improved a lot from last year.''
He wound up winning the Byron Nelson Championship a few months later for his first PGA Tour victory.
Patience surely will be required at some point over the weekend on what has shaped up as one of the best weeks of weather at Riviera - an abundance of sunshine and only a trace of wind. But the course figured to get tougher for the leaders in the afternoon as the greens get more foot traffic.
''It's a strong course, especially when it's dry and firm like it is,'' Baddeley said. ''If you miss it out of position, it's really hard to get the ball up-and-down. Today was good, because I made a couple good saves but coming in, I had some good looks and made them.''
Even among those who played early, it was hard to break away. A dozen players were within five shots of the lead, with half of the field still to finish the second round.
Baddeley was in the middle of the pack until he hit his approach on the 15th hole to about 8 feet. He followed with a short birdie putt on the par-3 16th, rolled in a birdie putt from 15 feet on the par-5 17th and finished it off with a 25-foot birdie on the 18th.
Charlie Beljan, who lost in a playoff last year, had a 68 and was two shots behind. Brian Harman had a 69 and was another shot back.
Jordan Spieth managed to get in the mix, especially after he was on the cusp of leaving early. The 20-year-old Texan had tough par putts on four straight holes at the start of his round. When he finally missed one on the fourth hole for his first bogey, he took off. Spieth birdied four of his last five holes for a 66, leaving him in the large group that was at 4-under 138.
''I putted great today, a lot of par saves on the front,'' Spieth said. ''I could have been 4- or 5-over at the turn, and instead I was at even, so very happy with the finish. Back in contention.''
Not so fortunate was Fred Couples, who had the low score in the group with Spieth and Webb Simpson until a poor finish. Couples made double bogey on No. 5, and then made bogey on his last hole for a 72 that left him at 2-over 144, which was likely to miss the cut.
Most frustrating for Couples was a tiny cut on the tip of his left thumb that opened up to the size of a dime, making it difficult for him to hang onto the club. Couples has gone his entire Hall of Fame career without wearing a glove.
Asked if it bothered him, he said, ''Yeah. I couldn't hit the ball.'' Couples made his 32nd appearance in this tournament.