By Mark Lamport-Stokes

With McIlroy initially failing to replicate the stunning form he produced earlier in the day on the way to a 3&1 semi-final win over third-ranked Briton Lee Westwood, Mahan took advantage with a seven-birdie display.

Northern Irishman McIlroy, like Mahan appearing in his first Match Play final, would have replaced Britain's Luke Donald as world number one when the rankings are issued on Monday had he claimed his first WGC crown.

(Reporting by Mark Lamport-Stokes; Editing by Gene Cherry)