The 19-year-old McIlroy had nine birdies and a bogey. He leads by one stroke over reigning European Tour Order of Merit champion Robert Karlsson of Sweden, with 60 players still to finish their round after fog delayed the start by 2 hours, 40 minutes.
Gonzalo Fernandez-Castano of Spain (66) is third, a stroke ahead of Gregory Havret of France and Alexander Noren of Sweden. Abu Dhabi champion Paul Casey, 2007 Order of Merit winner Justin Rose, Graeme Storm and Louis Oosthuizen all shot 68.
Three-time champion Ernie Els was 1 under after 12 holes and second-ranked Sergio Garcia was 2 under after 11.
McIlroy hit 17 greens in regulation and had 28 putts. He has eight top-10 finishes in his past 12 starts.
Sooner or later, Ill be able to win one, McIlroy said. But its not my main priority. My main priority is just to try to get in there in contention on the back nine on Sunday. If one falls my way, then thats fantastic.