Funk, who is in the midst of a three-week stay in Europe leading up to the British Open, briefly reached 6-under before a bogey on No. 16. O'Malley birdied four of his last seven holes to make his move among the leaders.
The most unusual round belonged to Romero, who closed with a pair of eagles to finish second in his most recent event at Wentworth Club. Romero sank eagle putts of 15, 18 and 20 feet on the fourth, 10th and 18th holes Thursday.
"I have never had three eagles in one round before," Romero said. "Coming after Wentworth it's unbelievable."
Britain's Lee Westwood was among a group of five golfers who shot 67 to stand one stroke off the pace.
Westwood has slumped of late, falling to 95th in the world and failing to qualify for the recent U.S. Open.
"I think missing the U.S. Open was a blessing in disguise," Westwood said. "The way I played recently I didn't deserve to be in the field and to be perfectly honest I wouldn't have enjoyed it."
Westood would have joined the group at 66 had he not bogeyed the last hole.
It was humiliating day for Seve Ballesteros of Spain, who shot an 89 and then was disqualified for signing an incorrect scorecard.
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