World number one Scottie Scheffler claimed a fifth victory of the year at the Memorial Tournament but only with a one-shot victory over Collin Morikawa.

The pair enjoyed a tense battle down the stretch separated by no more than two shots but it took a characteristic nerveless up and down from the back of the 18th green for Scheffler to close out a one-stroke victory with his opponent poised to force a play-off.

Scheffler's fist pump after holing from inside five feet, becoming the fastest player to five wins in a season since Tom Watson in 1980, showed how much pressure he had been put under.

"It's pretty amazing. I feel like I've had some close calls in this tournament," the American, who remarked on a "pretty surreal moment" to shake the hand of tournament host Jack Nicklaus after victory, said in his post-round interview at Muirfield Village.

"This is a tough place to close it out as you saw today, the course is playing so tough: firm and fast.

"Sixteen, 17 and 18 were playing really tough. It was a fun test of golf and I like it when it is hard.

"I didn't really do a whole lot great today but enough to get the job done."

Scheffler began the day with a four-stroke lead but having gone to the turn in one-over his advantage was down to two and when he left his birdie putt short at the par-five 15th, Morikawa – who picked up another shot at the short 12th – had a six-footer to draw level on nine under but missed on the low side.

Scheffler holed a crucial 15ft par putt at the next to take a two-stroke lead after his playing partner bogeyed from a similar position in front of the green only to hand it back at the next after coming up short with his approach.

Both players went long at the 18th but Scheffler, who had struggled on the greens all day, found a putt when he needed it for a two-over round of 74 to finish eight under.

Former US Open champion Matt Fitzpatrick shot a 69 to reach two under and take a share of fifth.

However, Rory McIlroy's preparations for Pinehurst did not go to plan after starting the day out of contention eight off the lead but looking for something positive to take into next week.

After a birdie and a bogey on the front nine to turn in level par, he had three bogeys and a double-bogey seven after hitting it in the water at the 11th in his next five holes on his way to a four-over 76 which left him two over in a share of 15th.