Paul Casey took a three-shot lead at the halfway stage of the Memorial Tournament by carding a 66 for the second day in a row in Ohio.

The Englishman, who has not recorded a victory in America since 2009, looked in fine form as he recorded six birdies and an eagle, but a dropped shot on the final hole saw him fall back to 12-under-par for the tournament.

Casey was helped in his climb to the top of the leaderboard by a disastrous day for Rory McIlroy as he threw away his first-round lead.

After shooting a 63 on Thursday, the former world number one struggled to replicate similar form, with three successive double-bogeys on the front nine summing up the day as his 78 left him nine shots behind the leader.

Bubba Watson is in second place heading into the weekend on nine-under, with fellow American Chris Kirk a further shot back.