Matt Fitzpatrick will take a one-shot lead into the final round of the 2022 DS Automobiles Italian Open after producing a stunning 69 in challenging conditions at Marco Simone Golf and Country Club.
Fitzpatrick started the day a single shot behind halfway leader McIlroy but turned in 36 after carding one bogey and no birdies on the front nine.
The wind changed as the final group reached the turn and shortly afterwards Fitzpatrick opened his birdie account at the tenth before rolling in for another on the 12th green to get to nine under.
He continued to impress in the tricky conditions and after saving par at the 17th, he birdied the last to take the outright lead.
McIlroy also finished his round with a birdie to post a level-par 71 which contained three birdies and three bogeys.
Rai, meanwhile, fired two eagles and two birdies in a flawless 65 to make a huge move up the leaderboard.
France's Victor Perez, American Kurt Kitayama and Australian Lucas Herbert were in a three-way tie for fourth on eight under.
Having opened his third round with a confident par save from seven feet, Fitzpatrick parred the next four holes before a bogey on the sixth saw him slip back to seven under.
He got his first birdie of the day at the tenth after lifting his approach to six feet, before going close again at the 11th.
Fitzpatrick holed his eight-foot birdie putt at the 12th to move to nine under before tapping in for a closing gain on the 18th green.
He said: "Really pleased with today. We had the wind switch on the ninth and the golf course just completely changed.
"It was a wind we had not played in all week. To me, I just felt like if I could just hang on and just avoid bogeys, I would put myself in a good position.
"Managed to pick up a few on the back nine. Delighted to be going into tomorrow with the lead."
When asked what it would mean to win on Sunday, Fitzpatrick added: "It would mean the world.
"I love coming to play the Italian Open.
"I love the country. I love playing golf here. The fans are fantastic and to win tomorrow, yeah, would be a great feeling."
McIlroy, who like Fitzpatrick will be hoping to represent Team Europe when the 2023 Ryder Cup is hosted at this venue, knows it will be tough to overcome the Englishman in the final round.
He said: "I felt like I played okay. Every birdie I made, I followed it with a bogey, so that was not good.
"But just when the wind got up there when we turned - I struggled with the putter all day but I think especially when the wind got up - I struggled just to sort of commit to reads, and 'do I play the wind, do I not play the wind?'.
"I held a couple of nice ones coming in but missed a lot of opportunities there at sort of the start of the middle of the round.
"Thankfully I'm still in it. Still only one shot back. I'll be in the final group tomorrow. So that was a big putt on the 18th to hole so I can keep an eye on Fitz and what he's doing.
"I know it will be a tough day. Fitz is very solid. These are the sort of conditions that he relishes. He's going to be tough to beat."
After holing some valuable par putts over the opening five holes, Rai got his first birdie of the day from 11 feet at the sixth.
Two more par saves from around ten feet at the seventh and eighth kept Rai's card clean before an eagle on the ninth catapulted him up the leaderboard.
And when he chipped in from just short of the 12th green for a second eagle of the day, Rai moved to eight under.
He followed that up with a 12-foot birdie at the 13th to get to nine under.
And with the wind picking up significantly in the closing stages of his round, Rai managed to par his way home to sign for a bogey-free 65.
Rai said: "I'm very pleased with how I played today overall."