Fleetwood sunk a birdie on the last to lead the way in the clubhouse at the end of his second round – but has been overtaken by J.B Holmes still on the course.
Fleetwood shot four under 67 to take advantage of some favourable conditions on Friday morning and looked in good spirits as he walked off the 18th green to a kind ovation.
He will now await his time slot for Saturday and his playing partners as the second day in Northern Ireland hots up for the Open Championship.
The Englishman, yet to win a major, stands at seven-under after his opening two rounds while Holmes, who had completed 12 holes of his second round was a shot ahead.
Fleetwood, who grew up playing links golf at Southport, delighted the crowd with a birdie on the 18th and he acknowledged the support by doffing his cap.
Australian Cameron Smith pushed himself into third place, at six-under, with two holes remaining in his round.
American Brooks Koepka, a four-times major winner, carded a 69 to follow his opening three-under 68 and move within two strokes of the lead.
Fleetwood dropped a shot on the tough par-three 16th but bounced back to birdie the last and complete a second round of 67.
“Yeah just about as pleased as you can be after two rounds,” he said. “Today was a little bit more grinding than yesterday.
And on his final hole birdie, he said: “I switched clubs really. The wind got up early.
“I had a seven iron out but went with an eight but the ball stuck right side of the green, so I was happy.
“The 18th is not the easiest approach to pick your target so I was happy just to hit a good shot.”
That set the early clubhouse target on seven under par with Holmes remaining in position to overtake him.
Koepka, who has finished second, first and second in the majors so far in 2019, looks ominously poised to mount another title challenge.
Fleetwood’s own form in the majors this year had been nothing to write home about but a fifth birdie of the day on the 15th took him to seven under and into a share of the lead thanks to Holmes dropping a shot on the ninth.
Tiger Woods had picked up another shot on the sixth to reach five over, with the early projected cut at one over as he and Rory McIlroy battle to stay in the competition over the weekend.