The Northern Irishman, who needs a top-seven finish to dethrone Luke Donald, birdied seven of his first 11 holes today - dropping a shot on another - to move 12 under par, one behind leader DA Points. The performance boosts his chances of reclaiming the world number one spot.
The American was enjoying an impressive round himself, shaving off three shots over the first eight holes, with McIlroy and a host of others behind him.
McIlroy was joined in second by Rickie Fowler, Ryan Moore, Webb Simpson and John Senden, with Stewart Cink and overnight pacesetter Nick Watney a shot further back.
Watney suffered an early blow, dropping two shots over the first six holes, and was just one clear of Geoff Ogilvy who carded the round of the day with a seven-under 65.
It was proving to be a low-scoring day for a lot of the field, with England's Lee Westwood signing in the clubhouse for a four-under 68, but that still left him well off the pace.
Should the Worksop man produce a final-day miracle and win the event, McIlroy would need a top-six finish to move back to the top of the rankings.
Westwood went round with Phil Mickelson, who matched him shot for shot and rests tonight on the same score.