McIlroy’s round left him two behind clubhouse leader Jeff Maggert.
The Irishman moved to three under after 10 but some long-game struggles caused two back-nine bogeys.
Pádraig Harrington matched McIlroy’s 68 but Graeme McDowell is nine behind after an opening 75.
World No 2 McIlroy went into the event after missing his last three cuts in a rare period of struggle for the 23-year-old.
McDowell, who like McIlroy started at the 10th, dropped to four over after eight with the 2010 US Open champion carding a double bogey at the 15th. Further shots went at the fourth and seventh and McDowell’s only birdie came at his closing hole.
Harrington produced a much steadier round of three birdies and a solitary bogey.
McIlroy hit only nine greens in regulation and missed more than half of his fairways but an excellent putting performance rescued him.
He twice saved par by holing out from more than eight feet and also slotted birdie putts of 16 and 10 feet.
Meanwhile, Lee Westwood carded a 64 to move three shots clear of the field at the Nordea Masters in Stockholm.
Westwood followed up his first round score of 68 by registering eight birdies to move to 12 under par ahead of a chasing pack of three that contains Scotland’s Lloyd Saltman.