At 5 beneath par in a single day, British pair McIlroy and MacIntyre had the chance to push on because the rain eased.
Only the Scot appeared prone to take it.
Playing the alternative facet of the course to the extra celebrated names, he quietly picked up 4 pictures in 10 holes to get to 9 beneath par however after hitting a shot from a hospitality verandah as he scrambled a par on the lengthy seventh, he bogeyed the ultimate two holes as he raced to beat the fading gentle.
Meanwhile, McIlroy birded the opening gap however was unable to seek out his kind on the greens earlier than the double bogey at 12 wrecked his card. It appears unlikely his lengthy look forward to a significant victory will finish right here on the place the place he received his final one in 2014.
Playing companion Justin Rose managed an eagle on the final to hitch him on 5 beneath par whereas fellow Englishmen Matt Wallace (67) and Aaron Rai (68) improved to seven and 6 beneath respectively.
Thirty one of many previous 34 winners of this event have been within the prime 10 on the midway stage and the closest challenger to the highest two is 26-year-old American Sahith Theegala whose wonderful 68 means he enters the weekend in third on 10 beneath par.
It was additionally an excellent day for 2020 US Open champion Bryson DeChambeau who shot seven birdies on his solution to a 65 as he completed in close to darkness to hitch Scheffler on 9 beneath.
He was joined within the prime 10 by 2023 runner-up Viktor Hovland who moved easily to eight beneath with a 66.
Lurking one place exterior the highest 10, 2023 winner Brooks Koepka matched magical iron play with inconsistent placing in his three-under 68. Five off the lead, the three-time champion stays a menace on this event.