PEBBLE BEACH -- Hunter Mahan seemed like the most likely candidate to take down leader Jimmy Walker on Sunday at Pebble Beach Golf Links.

But it was Dustin Johnson and unknown Jim Renner who made the most noise late in the final round of the AT&T Pebble Beach National Pro-Am. Mahan made a move after starting the day six strokes back, but his putting betrayed him on a damp and breezy day.

Mahan, seeking his first win since the WGC Accenture Match Play in February 2012, shot a second consecutive 72 for a total of 7-under 280 -- four shots behind the winner, Walker.

With Walker faltering late, the door was left open for veterans such as Johnson and Phil Mickelson. None could step through. Mickelson stumbled, in fact, shooting a 2-over 74 and finishing tied for 19th.

Johnson, who had the best round of the day with a 6-under 66, and Renner tied for second at 10-under 277, a shot behind Walker.

Johnson said he was "very pleased" with his round, in which he had nine birdies. He had a good run at an eagle on the par-5 18th before tapping in for birdie.

He hurt his chances on the par 3s, with bogeys on Nos. 5, 7 and 12.

"I played really well today," Johnson, a two-time AT&T champion, said. "It was tough out there. I hit a lot of great shots. I made a few bogeys and missed a short one on 14 for a birdie, but other than that I played great."

In solid form, Johnson has three top 10s in three starts this season, including a victory in the WGC-HSBC Champions and a tie for sixth at the Tournament of Champions.

Moreover, Johnson got to play this week with his future father-in-law, hockey great Wayne Gretzky, in the pro-am. Johnson is engaged with Gretzky's daughter, Paulina.

"The Great One" and Johnson finished tied for eighth at 24-under.

"I just enjoy this event, especially if you have a good group," Johnson said. "I've always had good partners. I played with Wayne the last two years, and before that with Jerry Rice. ... If you enjoy the people you're out with here, even if you're out here for a long time, it's not too bad."

Gretzky, likewise, enjoyed competing alongside Johnson. He was impressed with Johnson's play in tough conditions, for sure.

"Oh, forget it," Gretzky said. "Look at the weather and the conditions and how he played, it was so unique."

Renner, 30, after making the cut for the first time on tour since 2011, had a stellar 31 on the back nine. Renner missed the cut in his first four starts this season and did not play on tour in 2012 or 2013. He said he wasn't nervous on the big stage.

Renner drove the ball well, a must at Pebble Beach.

"Yeah, I had it going on that back nine," Renner said. "It was nice to get it going and make a couple putts. I hit a lot of quality shots, but it was nice to also roll them in."

He described his surprising runner-up finish as "pretty big. I had been struggling a little bit, and I really felt like I had it dialed in last week."

What part of his game needed the most work?

"Well, where do I start," he said. "I changed all my shafts in my irons and my woods, so there you go."

Mahan may have worn the biggest scowl in the end.

He appeared poised for something special after a birdie on the 12th hole to improve to 8-under. Then he bogeyed the par-3 17th hole after pushing his tee shot into the right rough into the wind. Then Mahan found the rough twice on 18 before leaving a birdie putt an inch short.

It was that kind of a day for Mahan, who struggled on the greens. He left the course without a comment.

He seems to be knocking on the door each week. Mahan led the RBC Canadian Open in July 2013 after two rounds but withdrew after his wife, Kandi, went into labor. Last week, Mahan finished fourth after a final-round 68 at the Phoenix Open.

Mickelson, making his 20th consecutive appearance in the tournament, likewise was betrayed by his putter. After opening the day eight back, he failed to ignite the large gallery shadowing his every move.

"This is the worst putting week I've had in a year and a half," Mickelson said. "And I'll get that fixed, because I've been putting terrific for the last year and a half. But this was a horrible performance on the greens."

Mickelson was, however, pleased with his ball striking and said he enjoyed playing Pebble Beach in "these conditions."