Fitzpatrick, who edged out Scheffler to win his sole major at Brookline, is the closest challenger after willing in a 24-foot par putt on the 18th for a 66.
The 30-year-old has been on an upturn in form since shooting 78 and 72 to miss the cut in The Players Championship in March – which he described as the lowest point of his career – following a run of just one top-10 finish in the previous year and a fall outside the top 80 in the world rankings.
As spring gave way to summer, coaching changes brought consistency, with a tie for fourth place at last week’s Scottish Open showcasing his renewed confidence.
Portrush is the scene of Fitzpatrick’s best Open finish – although the word ‘best’ is doing some heavy lifting, given he was tied for 20th place at the Antrim course in 2019.
However in his 10th appearance at the event, he is right in the mix to become the first Englishman to lift the Claret Jug since Sir Nick Faldo at Muirfield in 1992.
“I’ve given myself an opportunity, but there’s still a long way to go,” Fitzpatrick said.
“There’s nothing better than being in contention. It feels a bit uncomfortable at the time, but you want to feel that. It means you’re doing something right.
“It’s an exciting position for me to be in given where I was earlier this year.”
Tucked one behind Fitzpatrick and two adrift of Scheffler are 2023 Open champion Brian Harman of the United States and Li Haotong of China.
World number 111 Li has dropped just one shot in posting a pair of 67s, while Harman plotted his way round in a blemish-free 65.