The four-time major winner birdied the first from six feet, two-putted the par-five second for another and also holed from 10 feet on the fourth to move to 11 under par, two behind Sullivan who had also birdied the second.

McIlroy leads Danny Willett by just 1,613 points in the Race to Dubai but was now four shots ahead of the Englishman, who had carded two birdies and one bogey in his first eight holes.

Former US Open champion Justin Rose could also win his second money list title but needs to finish second or better and was alongside Willett on seven under after cancelling out a birdie on the second with a bogey on the fourth.

Argentina’s Emiliano Grillo, who almost hit McIlroy with a tee shot during the Frys.com Open last month before going on to win his first PGA Tour title, was alongside the world number three on 11 under, with former Masters champion Charl Schwartzel a shot further back.

The most spectacular golf of the day so far had come from England’s Lee Slattery, who played his last five holes in six under par thanks to eagles on the 14th and 15th and birdies on the next two holes.

A par on the last gave Slattery an inward nine of 30 and a third round of 68 to lie one under.

Sullivan's lead was down to a single shot when he carded just his second bogey of the week on the fourth after failing to get up and down from a bunker.

And although the 29-year-old soon restored his two-shot lead with a birdie from 12 feet on the next, McIlroy closed the gap once more by chipping to two feet on the par-five seventh to set up his fourth birdie of the day.