|Houston Open third-round leaderboard|
|-14 J Spieth (US); -13 S Piercy (US), J Wagner (US), A Cook (US); -12 S Stefani (US); -11 K Day (Eng), P Casey (Eng), C Howell III (US), R Henley (US); Selected others -9 S Garcia (Sp); -8 P Mickelson (US); -7 J Rose (Eng); -3 P Harrington (Ire), E Els (SA), V Dubuisson (Fr)|
Englishmen Kelvin Day and Paul Casey carded rounds of 68 to earn a share of sixth place, three shots adrift, after round three of the Houston Open.
They reached 11 under but trail world number four Jordan Spieth who moved up from fifth with six birdies in his 67.
Phil Mickelson, one shot off the halfway lead, dropped six shots in his 75 and is six shots back in joint 18th.
US Ryder Cup player Patrick Reed had a hole-in-one with a five-iron at 16, the 20th ace on the PGA Tour this season.
Mickelson claimed a share of the lead after a birdie at his first hole but unravelled into some untidy play, with a double bogey at the fifth and a series of wayward shots.
Playing alongside the five-time major champion was Austin Cook, a 24-year-old from Arkansas, who won a qualifying tournament on Monday to gain a place in only his second PGA Tour event.
He led the tournament before a double bogey at the 15th, but birdied 17 in a round of 70 and is only one shot behind Spieth, who heads four fellow Americans at the top of the leaderboard.
Casey, a three-time Ryder Cup veteran, most recently in 2008, won the KLM Open on the European Tour last year and was second at the Northern Trust Open in February, but his sole victory in America remains a play-off success at this event in 2009.
The 37-year-old world number 48 had four birdies in five holes on his front nine.
Day, 27, the Surrey-born world number 1,045 who plays on the second-tier web.com Tour, did not drop a shot in round three and had four birdies on the back nine.
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