Rahm's blistering 65 sets early pace at Bay Hill

Jon Rahm regained top spot in the world rankings with his third win of the year at February's Genesis Invitational

World number one Jon Rahm shot a seven-under-par 65 to take a two-stroke lead after the first round of the Arnold Palmer Invitational at Bay Hill.

Chris Kirk, who won last week's Honda Classic, is in a three-way tie for second with fellow Americans Cameron Young and Kurt Kitayama.

Defending champion Scottie Scheffler is one stroke further back on four under.

Rory McIlroy opened with a bogey after finding a greenside bunker and it signalled the start of a see-saw round for the Northern Irishman.

The 33-year-old, ranked third in the world behind Rahm and Scheffler, made three birdies but a double bogey at the sixth and a dropped shot at the 14th - where he again found sand - proved costly as he signed for a one-over 73.

It was a more positive day for Englishman Aaron Rai, who started on the back nine and is well placed alongside Scheffler after a 68.

Jordan Spieth, Xander Schauffele and Patrick Cantlay are also on four under in a high-calibre field that contains 43 of the world's top-50 players.

They are competing for a purse of £17m, of which more than £3m will go to the champion.

US Open champion Matt Fitzpatrick and former Masters winner Danny Willett both recovered from double bogeys to finish with two-under 70s.

Fellow Englishmen Tyrrell Hatton and Luke Donald also made encouraging starts to sit one under alongside Scotland's 2011 winner Martin Laird.

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