Aaron Baddeley charges into the lead at Riviera

Fred Couples is a sentimental favorite to win the Northern Trust Open on Sunday, a 51-year-old with emotional loyalty to the Riviera Country Club course where he has won two titles.

Kevin Na is another sentimental favorite, a local kid from Diamond Bar High who is hoping his first PGA Tour win might give his father a happy helping of hope as he battles leukemia in Korea.

Couples and Na are both at nine-under-par 204 after three rounds, and that’s almost good enough to lead.

But not quite.

Aaron Baddeley, a shaggy-haired 29-year-old from Australia, who had to play 22 holes Saturday, birdied four of five holes in the middle of his third-round four-under-par 67 and has a one-stroke lead at 10-under 203.

Couples almost energized a noisy gallery on the 18th hole when he ran a 25-foot birdie putt just off the right corner of the hole.

Before hitting the putt, Couples was bending and cracking and stretching his sore back. When it was his turn, Couples tidied up the green, picking up tiny blades of grass no one else saw, but he couldn’t quite get that final birdie.

On a day that began sunny and a little warm and included rain, wind, a little more sun and then more rain, Couples made only one mistake and it came during the worst of the downpours.

A chip on the par-four 10th hole was hit too strongly and the ball slipped off the back of the green.

“I was thinking to myself, as I was bogeying 10, ‘Wow, this is going to be brutal.’ But it stopped after 11,” he said of the rain.

And Couples’ immediate response to the bogey was one of his two birdies in the round, one immensely appreciated by his wet gallery.

Baddeley, who finished tied for sixth last week at Pebble Beach, has two PGA Tour wins but none since 2007. The Australian, who was born in New Hampshire while his father worked as chief mechanic for auto racer Mario Andretti, started his lead-taking stretch with a birdie two on the sixth hole. He passed Couples with birdies on Nos. 8, 9 and 10.

But Baddeley, who didn’t finish Friday because of darkness, thought that a birdie on the 18th early in the morning, to complete his second round, was particularly important.

“That was nice,” he said. “It gave me good confidence going into [the rest of Saturday], knowing the game is still right there.”

Na had seven birdies and three bogeys during an inconsistently adventurous round. Afterward, he remembered how his father had brought him to Riviera in 1995 to watch the tournament. Late last year his father learned he had leukemia and is in his native South Korea receiving treatment.

After this tournament ends, Na said, his mother is flying back to be with his father. “I’d really like to send this trophy with her to him,” he said.

While Na is hoping for his first win, Couples is aiming for his 16th on the PGA Tour. A victory would make him the oldest winner in 36 years. He would also become the third player (along with Sam Snead and Ray Floyd) to have wins in four decades.

But Couples wasn’t thinking about history Saturday. Just about shooting 70 and being in contention. “I’m in good shape,” he said. “I hung in there, I didn’t hit the ball exceptionally well, but I hit it solid, which is what I needed to do.”

diane.pucin@latimes.com

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