CHARLOTTE, North Carolina (REUTERS) - Rory McIlroy won for the second time in three weeks and shattered the tournament record when he clinched a seven-stroke victory at the US$7.1 million (S$9.38 million) Wells Fargo Championship on Sunday.

McIlroy, who started the final round with a four-shot lead, was never seriously challenged as he compiled a steady three-under-par 69 on a languid afternoon at Quail Hollow, where he notched his first PGA Tour victory five years ago.

The Northern Irishman finished at 21-under 267, a tournament record low score by five strokes, while Americans Webb Simpson (72) and Patrick Rodgers (68) tied for second on 14-under.

McIlroy's margin of victory was only one shy of his record eight-shot wins at two major championships, the 2011 U.S. Open and 2012 PGA Championship.

It was his 18th professional victory worldwide, and his third this year.

When he won the World Golf Championships-Match Play two weeks ago, he joined Tiger Woods (29) and Jack Nicklaus (17) as the only players to win 10 events before their 26th birthday on the PGA Tour in the last 75 years.