AUGUSTA, Ga. — One round now separates Rory McIlroy from one of golf’s most elite constituencies. If on Sunday he can reel in Patrick Reed, the Masters’ 54-hole leader, McIlroy will become the sixth man — and the first since Tiger Woods in 2000 — to complete a career grand slam.

Playing in the group directly ahead of Reed, McIlroy carded a seven-under-par 65 in the third round, tying for Saturday’s low score with Rickie Fowler and Jon Rahm, who are in third and fourth place, respectively. With his 54-hole total of 11-under 205, McIlroy finished the day three strokes behind Reed, who posted his third consecutive sub-70 round, a 67, on the soggy Augusta National course.

“I’m just going to do my thing and stick to my game plan and go out and enjoy my Sunday,” Reed said of his final-round pairing with McIlroy. “I’m not out there to play Rory. I’m out there to play the golf course. If I go out and I feel pleased with how I play, then, you know, it should be an enjoyable Sunday night.”

Reed, 27, has never won a major, though he finished in a tie for second at the P.G.A. Championship last year. On Sunday, he will aim to become the first player at the Masters ever to shoot four rounds below 70 — and also to make McIlroy wait at least another year to claim his first green jacket.