Montgomerie met Friday's deadline for next week's World Golf Championship event at La Costa Resort, giving the field all but two of the top 64 players in the World Ranking.
Thomas Bjorn previously withdrew with an injured shoulder, while Jose Coceres is still recovering after breaking his arm playing soccer.
The first-round pairings will not be final until 5 p.m. Monday. Any player who withdraws after that time will not be replaced in the field.
Bob May is the first alternate. Had Montgomerie withdrawn, May would have played Tiger Woods, the No. 1 seed, in a reprisal of their phenomenal duel in the 2000 PGA Championship at Valhalla. Woods birdied the last two holes, then won in a playoff.
As it stands, Woods will face Peter O'Malley in the first round Wednesday. O'Malley did not sound overly concerned.
'Tiger is not as untouchable as he was 12 months ago,' O'Malley said earlier this week. 'Anything can happen in 18 holes of match play. I definitely give myself a chance.'
Woods reached the quarterfinals in 1999 and was beaten by Darren Clarke in the final two years ago at La Costa. He was among more than two dozen players who skipped the event last year in Australia.
Still, it was one of his top goals besides the majors, which is one reason he skipped the Nissan Open this week to get over remnants of a virus.
Barring no changes by Monday evening, other first-round matches among top seeds will be Phil Mickelson (2) against John Cook, David Duval (3) against Kevin Sutherland, and Sergio Garcia (4) against Lee Janzen.
Top seeds mean little in golf. Woods in the only played seeded 10th or higher to reach the final in the first three years of the tournament.
The draw provides a few intriguing pairings, none better than Jose Maria Olazabal against Justin Leonard.
They last were matched against each other on the final day of the Ryder Cup, when Leonard holed a 45-foot birdie putt to cap the United States' historic comeback.
John Daly, playing in his first WGC event, will play Rocco Mediate, while Vijay Singh gets Toru Taniguchi, who beat Singh in the quarterfinals last year in Australia.
Montgomerie would play Scott McCarron.