Persistent crosswinds tested the players on Thursday but the conditions were as calm as they have been all week for the early starts on Friday.
Despite that, however, McIlroy played his first five holes in one over, a bogey on the par-three 14th putting him on the backfoot before he picked up his first of the round at the next.
Having birdied 16, 17 and 18 on Thursday, McIlroy had to settle for three pars on Friday but he prompted a huge roar from the crowd with an eagle at the first, made possible by a booming 333-yard drive down the fairway.
“I wish every hole was that easy,” he quipped after his round.
That was as good as it got for the 35-year-old, though. A bogey five at the fifth after finding trouble off the tee brought him back to four under but he is primed to be a central protagonist over the weekend.
So, too, is Lowry. Like McIlroy, the 2019 Open champion did not have it all his own way on Friday, cutting a despondent figure after de-greening his eagle putt at the driveable par-four 16th, leading to an unlikely bogey.
But the 37-year-old has spoken positively of how he has handled setbacks this year and he reeled off three birdies around the turn to reach two under.