Rocco Mediate is alone in fifth place at 7-under-par 209, while Tim Clark, Brad Faxon, Tim Herron, Dicky Pride, Rory Sabbatini and overnight leader Jim Furyk are one stroke further back.
Love started quickly on the back nine at Spyglass Hill. He rolled in a 50-foot birdie putt at his first hole and followed that with a four-footer at the next. Love, who won this event in 2001, stuck a sand-wedge within four feet at the par-5 14th to set up his third birdie of the round.
The 38-year-old however faltered at the 15th and 17th to drop back to 6-under. Love, who was paired with Faxon, three-putted the 15th from 25 feet and was unable to get up-and-down for par at the 17th.
'It doesn't hurt playing with (Brad) Faxon, he is Mr. Positive,' Love said. 'It was fun to get paired with him and I think what's working for me is just a good attitude.'
Love then began his climb up the leaderboard around the turn at No. 1 on Spyglass. He rolled in a 20-foot putt at the par-5 first. He continued his hot play with a birdie at the par-3 third. Love then vaulted into the lead when he rolled in a 12-foot eagle putt at the par-5 seventh.
'It's nice to come out on top after three days,' said Love, who has held the 54-hole lead 19 times in his career, leading to seven of his 14 titles. 'But you know, we've got another day at Pebble and I'm looking forward to it.'
Love and the rest of the field have enjoyed dry conditions throughout the tournament. Sunday's forecast calls for more of the same, so touch around the greens will be key.
'It's always good to have a two-stroke lead, but you know, like I said, the greens are firm, fast and playing tricky, it's like the U.S. Open,' said Love. 'You still have to go out and play hard just like any tournament.'
Weir was the story of the day early on at the Pebble Beach Golf Links, where the remainder of the field will play the final round on Sunday. He posted three birdies and two eagles in a six hole stretch on the front side.
Weir, who won last week's Bob Hope Classic, rolled in a 15-foot eagle putt at the second to get started. He followed that with a birdie at the next. Weir birdied the fifth after sticking a 7-iron within five feet.
The Canadian continued his roll with his second eagle at the sixth when he holed out from 35 yards. Weir drained an eight-footer for birdie at the next to climb to 7-under for his round.
Weir lipped out a birdie putt on eight that could have given him a share of the nine-hole course record of 28. Brent Schwarzrock tied the mark of 28 last year after Love and Spike McRoy set the record in 2001.
Weir, the 2001 Tour Championship winner, faltered on the back nine. He bogeyed the 12th and 18th to fall back to minus-5 for his round. He also missed birdie chances on 10 and 15.
'It was an exciting front nine, obviously,' said Weir. 'I played outstanding today. I played just as well on the back nine. The score didn't indicate that, but I struck it just as good or better on the back nine.'
Pampling began his day on the back nine at Poppy Hills, the final of the three courses being used for the first three rounds. He birdied two of his first three holes to get to 8-under. However, he faltered at the next, before carding consecutive birdies starting at the 15th.
Around the turn, Pampling notched a kick-in birdie at the second. He bogeyed the next two holes, each time due to three-putting.
Paul Stankowski, Phil Tataurangi and first round leader Kevin Sutherland are tied at 5-under 211.
The 54-hole cut fell at 2-over-par 218. Among those who did not qualify for the final round was last year's winner Matt Gogel, who finished at 15-over-par 231 to become the first defending champion this season to miss the cut.