Shane Lowry's putter thawed out late in the afternoon as he birdied three of his last six holes to finish tied 14th behind Jordan Spieth in the AT&T Pebble Beach Pro-Am.

As Spieth coolly converted his six-stroke overnight lead into a four-stroke win on 19 under thanks to an immaculate closing 70, Lowry also shot 70 to win $108,160 and leave with some satisfaction after an excellent week from tee to green.

For a while it looked as though it might be a frustrating Sunday for the Offaly man, who was tied for eighth going into the third round but holed little over the weekend until late on Sunday.

Even though he had 32 putts in the final round, he had just 13 on the back nine, rolling in 14 footers for birdies at the 14th and 16th before chipping dead to set up his fifth birdie of the day at the 18th for a seven-under par total.

Lowry had two-putted the par-five second for birdie. But when he three-putted the third for bogey and then double bogeyed the 192-yard fifth, tugging his tee shot into sand before failing to get out at the first attempt, a top 20 finish looked unlikely.

He got back to level par immediately with a birdie at the 519-yard sixth but he had a nine-footer for an eagle there thanks to a pinpoint 238-yard approach.

In fact, he missed birdie chances from 15 feet at the seventh and nine feet at the ninth, racking up 19 putts on the front nine to turn for home 13 shots off the pace in a share of 24th.

He turned it around on the homeward trip, using the blade just  13 times as he came home in three under and moved up to 76th in the FedEx Cup points list.

Seamus Power slipped from 101st to 107th in the FedEx after a one under 71 left him tied for 39th on four-under par.

The West Waterford man picked up $26,640 for his week's work but with a final round scoring average of 72.00, he knows that number must come down.

As for Spieth, he played conservatively and hit 17 of 18 greens as his playing partner Brandt Snedeker got to withing four shots at one stage on the front nine but never threatened to go on a charge.

Spieth's lead was reduced to three when eventual runner up Kelly Kraft birdied the 11th to get to 15 under par.

But the Texan, a pal of Spieth's from Dallas, parred his way home instead for the best finish of his PGA Tour career.

"That's a dream round when you're leading by a bunch," said Spieth, who birdied the par-five second and had to wait until the iconic 17th, where a 29 footer toppled in, for his second birdie.

Former US Amateur champion, Kraft shot 67 and finished second, four behind Spieth on 15 under with Dustin Johnson third on 14 under after a 68 and Snedeker fourth after his 70.

Spieth said caddie Michael Greller told him on every tee, "Keep playing boring golf."

"I don't like boring golf," he said. "But that's what was needed today."

It was Spieth's ninth PGA Tour win and while he remains at world No 6, he could move to world No 2 if he wins the Genesis Open at Riviera this week.

Johnson could go to No. 1 by winning in Los Angeles and replace Day, who shared the 36-hole lead at Pebble Beach but fell 10 shots behind with a 75 on Saturday.

The Australian ended up tied fifth alongside Gary Woodland (65) and Torrey Pines winner Jon Rahm (68).