Kribel, the runner-up in the 1997 U.S. Amateur, shot a 69. He was in command with four birdies over the first six holes at the Clearwater Resort, but made three bogeys in the span of five holes on the back nine to surrender the lead.
The day's best round was turned in by Andrew McLardy of South Africa, who took sole possession of third place at 11-under 205. He tallied an eagle, five birdies and one bogey for a 66, matching the course record posted by three others this week.
O'Malley, one shot off the lead after the first 36 holes, did a good job keeping pace with Kribel early in Saturday's round. Birdies at the second, fifth and sixth holes kept O'Malley within two heading to the back nine, then Kribel bogeyed the 12th and 14th to slip back into a tie with O'Malley at 11-under-par.
The players traded birdies on the par-4 15th, but Kribel dropped a shot at No. 16 to hand the top spot to O'Malley. Both closed with birdies, making it the first time either had birdied the 18th this week.
O'Malley, 36, has three European Tour titles on his resume, the most recent a come-from-behind win at last year's English Open. But he may now be best known for his first-round upset of world No. 1 Tiger Woods at last month's WGC-World Match Play Championship in California.
The 64th seed in the 64-man field at La Costa, O'Malley only made it into the tournament when Jose Coceres and Thomas Bjorn pulled out with injuries.
O'Malley tied for fourth at last week's Jacobs Creek Open Championship in Australia, the first of two season-opening Buy.Com Tour events co-sanctioned with the Australasian Tour.
Americans Rich Barcelo (69) and Brad Ott (72) finished in fourth place with Anthony Painter (72) of Australia at 8-under. Germany's Alex Eke (68) was six shots behind the leader at minus-seven.
Former Georgia Tech star Bruce Molder, who shot 66-69 to share the first and second-round leads with Kiel, struggled to shoot a 5-over 77 on Saturday.
Even par for the day with three birdies and three bogeys through 11 holes, Molder's round came apart with three straight bogeys from the 12th and a triple-bogey six at the par-3 16th. He managed to birdie the 18th to finish alongside 20 other players at 4-under-par 212.
Molder was the runner-up last week in Australia.
Full field scores from the Clearwater Classic