Mark Foster, the 2003 dunhill championship winner, posted a 4-under-par 68. He was joined in a tie for second place by Nick Dougherty and Danny Chia. Seven other players are one stroke further back at minus-three.
Montgomerie opened his round on the 10th tee of the Masters Course at Laguna National Golf & Country Club. The Scotsman had a steady start with five straight pars to open his round.
The 41-year-old birdied the par-5 15th to move into red figures. Monty came back with a birdie at 17 and followed with another at 18 to make the turn at minus-three.
Montgomerie picked up his fourth birdie at the par-3 third. He moved to 5-under with a birdie at the fifth, another par-3.
'I have always prided myself in the number of twos I have had in a round, I have made an inordinate number of twos in my career, I'd love to add it up, and again I made three today,' Montgomerie said. 'I have always said that if I am playing well, my iron shots are good and making twos is always a sign of me swinging the club well.'
Monty collected his third birdie on a par-3, and sixth overall, at the eighth. He closed a bogey-free round with a birdie at the par-4 ninth.
'I never missed a green today, hardly missed a fairway and that was as good as I have ever done in these circumstances,' said Montgomerie. 'To start out a year where the pressure is on for me to get my world ranking back to where it should be, and I know it should be in the top-20, this is a fantastic start.'
Foster got off to a quick start with birdies at two and three. He cruised to five straight pars before dropping in his third birdie at the ninth. The Englishman birdied the 11th to get to minus-four, before parring his final seven holes.
Dougherty opened his round with six consecutive pars. He then picked up back- to-back birdies from the seventh. Around the turn, he converted birdie opportunities at the 13th and 15th to tie for second.
Chia picked up three birdies over his first eight holes. He tripped to a bogey at the ninth, but fought back with a birdie at No. 10. He wrapped birdies at 16 and 18 around a bogey at 17 to finish at minus-four.
Soren Hansen and Maarten Lafeber head a group of players at 3-under-par 69. They were joined there by Adam Groom, Soren Kjeldsen, Jason Knutzon, Jean- Francois Lucquin and Brett Rumford.
Among the eight players tied at minus-two is Lee Westwood, who is playing in this event for the first time. Westwood owns 16 wins on the European Tour and is a four-time Ryder Cup performer for the Europeans.
Lian-Wei Zhang, the 2003 champion here, posted an even-par round of 72 and stands in a large group tied for 30th place.