In a chaotic finish to the second round of the BMW PGA Championship, Åberg and McIlroy won their own personal battles down the storied par-5 last hole at Wentworth, where for a while nine balls were regularly in play as players backed up to complete their rounds in close-to-dark conditions.
Most of the light shining on the green came from the giant illuminated scoreboard as Åberg, the 23-year-old Swede tipped to be the next big thing in golf, rolled in a putt from 4 feet for a 6-under 66 to tie for the lead with compatriot Sebastian Söderberg (64) at 10-under par.
McIlroy then two-putted for birdie from 45 feet to finish off a round of 71 and move to 1 under, which should see him make the weekend on the number. He will have to wait until Saturday morning to be sure, though.
A tournament containing all 12 members of Europe's Ryder Cup team is set for an exciting conclusion, with Åberg -- one of the most talked-about players heading to Rome -- being chased by plenty of big names.
Tommy Fleetwood (66) was a shot back in a four-way tie for third place that included Adrian Meronk, the Polish golfer who is using the pain of his Ryder Cup omission to underpin a run for the most prestigious title on the European tour.
Meronk still feels aggrieved at not being one of Luke Donald's captain's picks after winning three European tour events since last July. That makes him a big threat heading into the weekend.
"I am trying to turn that disappointment and anger into fuel," said Meronk, who has a better score this week than 10 of Donald's team. "I definitely think it is wrong. I feel I've deserved it."
Rahm produced a fine recovery after dropping three shots in his first three holes, responding with an eagle from 12 feet at the par-5 4th and six birdies in his final 10 holes.
Åberg's finish was pretty similar as he made five birdies in his final seven holes, including three straight from No. 16.
Åberg turned pro in June and has already won on the European tour, at the European Masters in Switzerland at the start of September, to help secure a captain's pick for the Ryder Cup. Now he could be taking a victory in the tour's flagship event to the biggest team event in golf, further underlining his credentials as a star for the future, if not the present.
McIlroy, on the other hand, looked to be battling with his swing for much of the day and cut a frustrated figure in the final holes as Åberg, playing in the same group, piled up the birdies.
"I haven't had my best over the last couple of days, but I don't feel like I'm too far away," McIlroy said, "so hopefully I get an opportunity to play another couple of rounds here, and you know, try to finish the week off on a good, positive note."
Söderberg had taken the clubhouse lead despite a bogey on the first hole. He made seven birdies and finished with an eagle from over 15 feet at the 18th.
The Associated Press and Reuters contributed to this report.