Video: Spectator's backside prevents Jordan Spieth's wayward tee-shot from finding the water
Andy Sullivan followed a flying start with an equally fast finish to further impress Ryder Cup captain Darren Clarke by setting the clubhouse target in the Abu Dhabi HSBC Championship.
After the start of play had been delayed by two hours and 45 minutes due to thick fog, Sullivan began his round with three straight birdies and ended it the same way to card a second successive 67.
McIlroy started his second round with eight straight pars before a bogey on the ninth, where his pushed drive finished in rocks on the edge of a lake, dropped him back to five under par.
Spieth was faring even worse with bogeys on the fourth and fifth, and the world number one was lucky not to drop more shots on the ninth, where his drive was heading towards the water - on the other side of the fairway to McIlroy - before hitting a spectator in the backside and finishing in the rough.
The world number one found the edge of the green with his approach and left his birdie attempt inches short, leaving him on two under par and just one shot inside the projected cut mark.
In contrast, DeChambeau had started his round on the back nine and birdied the 10th and 12th to join Sullivan in the lead on 10 under par.