Summerhays storms into lead as struggling Dufner shoots 77

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Daniel Summerhays capitalised on Jason Dufner's stunning capitulation to take a three-stroke lead after the third round of the Memorial Tournament.

Dufner was unable to stop the rot as he watched his five-shot advantage atop the leaderboard vanish following a five-over-par 77 on Saturday.

The four-time winner on the PGA Tour threatened to run away with the tournament after breaking the event's 36-hole record at Muirfield Village on Friday but he faded dramatically, holing six bogeys and a double-bogey.

Things did not go according to plan for Dufner from the outset following four consecutive bogeys, starting at the second hole.

And Summerhays pounced with a four-under-par 68 to take control heading into Sunday's final round.

Summerhays had five birdies and a bogey to be clear at 13 under through 54 holes - ahead of Matt Kuchar (67).

Bubba Watson (68) and Justin Thomas (69) are level with Dufner at nine under, while Rickie Fowler (72) is a shot further back.

Former world number one Jordan Spieth is six shots off the pace after his third-round 71.

Spieth dropped four positions following a mixed day, which included six birdies, three bogeys and a double-bogey.

Kevin Streelman (67) and Kevin Kisner (70) are also seven under.

Phil Mickelson posted a 72 to be four under, a shot ahead of Australian pair Jason Day (67) and Adam Scott (71).