Casey - plenty to smile about.

Paul Casey turned in a stunning performance in the second round of the US Open at Oakmont as Nick Dougherty suffered a nightmare.

Englishman Casey shined, shooting a four-under-par 66, the lowest round of the tournament, to vault into contention at the season's second major.

Casey is just three shots behind leader Angel Cabrera of Argentina.

Cabrera entered the day at one under but was able to go no lower, ultimately finishing with a 71 for a 36-hole total of 140 for level par.

American Bubba Watson is alone in second at one over after shooting a 71.

The USGA announced in the morning that the greens were back up to their practice round speed after Wednesday's thunderstorm, but that mattered very little to Casey, in contrast to the rest of the field.

After digging himself a hole yesterday, Casey dug in today, firing five birdies with just one bogey to lie at a three-over after 36 holes.

"A 66 is way beyond my expectations and I am still a bit surprised at the score I shot today," Casey said.

"This is right up there in terms of my best round ever. If I had kept the bogey off the card, without a doubt it would have been.

"But I consider the US Open to be the toughest test in golf. This is possibly the toughest golf course I have played and I feel very, very lucky to have shot 66 on it."

Dougherty, who led after the first round on two under, failed the test of Oakmont miserably a day after passing it in flying colours.

Starting on hole 10, Dougherty had three pars to start his round before a birdie at 13 put him at three under, but he immediately ran into trouble at the next.

A three-putt bogey there was followed by a double-bogey six on the next, and another dropped shot on the 18th took him out in 38.

The back nine was no kinder to Dougherty as four more bogeys led to a seven-over 77.

At five over, Dougherty is in a tie for 13th and still clearly in the hunt.

"Seven over is a bad score but it has put me in the tournament," Dougherty said. "I'm relatively pleased to be honest."

Another Englishman, Justin Rose, shot a second consecutive 71 to stand at two over.

Rose is tied for third with Aaron Baddeley, Stephen Ames and Niclas Fasth.

Ames shot a 69 to join Casey as the only players to shoot sub-par second rounds.

"It's a better 71 than yesterday," Rose said.

"Yesterday I walked off the course being a little disappointed whereas today I'm delighted with 71."

But there is no doubt that it was Casey's day at Oakmont.

Starting his round on the 10th after a 77

yesterday, Casey got off to a flying start with a birdie and kept up the momentum throughout his front nine.

Playing in his fifth US Open, the 29-year-old added birdies at the long par-five 12th, 14th and 17th.

His lone mistake came at the 18th where his approach was off to the right and long, settling in the rough just off the green.

He chipped to about 10 feet but two-putted for his first bogey of the day.

"I don't know what the difference was, yesterday was disappointing," Casey said of his 11-shot swing.

"I think I got maybe a little wrapped up in technique, in trying to swing the club correctly rather than hitting golf shots. It's only my own fault."

Joining Dougherty at five over is Tiger Woods, who is still in the hunt for a third US Open title after a 74, and Graeme McDowell who is also at five under after a 72.

It was a struggle for the world number one as he carded six bogeys and just two birdies but remained in contention.

"I don't know what the average score was today but I think I shot under par," Woods said.

"It was playing hard out there, it was really playing hard and the greens got really quick."

Phil Mickelson looked like he was going to join Casey in carding a low round but he undid any momentum he built with birdies at the fourth and sixth with a horrible close to his front nine.

The left-hander double-bogeyed the seventh and added bogeys at the eighth and ninth Things got no better for him on the back nine as he started his inward half with a double-bogey at the 10th.

A pair of pars were just temporary relief as Mickelson bogeyed 13, 15 and 16 and 18, sprinkling in a birdie at the 14th to lie at 11 over for the championship and miss the cut by one shot.

It snapped Mickelson's cut streak of 30 consecutive majors.

The last time he failed to make it to the weekend in a major was in 1999 at the British Open.

Mickelson was hampered by a wrist injury this week and was obviously unhappy with his performance.

"It's disappointing to dream as a kid about winning the US Open and spend all this time getting ready and have the injury," he said.

Collated totals (USA unless stated):

140 Angel Cabrera (Arg) 69 71

141 Bubba Watson 70 71

142 Aaron Baddeley (Aus) 72 70, Justin Rose (Eng) 71 71, Stephen Ames (Can) 72, 69, Niclas Fasth (Swe) 71 71

143 Paul Casey (Eng) 77 66

144 Carl Pettersson (Swe) 72 72, Tom Pernice Jnr. 72 72, Brandt Snedeker 71 73, David Toms 72 72, Scott Verplank 73 71

145 Chad Campbell 73 72, Graeme McDowell (NIrl) 73 72, Nick Dougherty (Eng) 68 77, Tiger Woods 71 74, Jerry Kelly 74 71, Peter Hanson (Swe) 71 74

146 John Rollins 75 71, Jim Furyk 71 75, Jason Dufner 71 75, Lee Janzen 73 73, Olin Browne 71 75, Stuart Appleby (Aus) 74 72, Stephen Ames (Can) 73 73, Shingo Katayama (Jpn) 72 74

147 Hunter Mahan 73 74, Anthony Kim 74 73, Boo Weekley 72 75, Michael Putnam 73 74, Lee Westwood (Eng) 72 75, Pablo Martin (Sp) 71 76

148 Steve Stricker 75 73, Vijay Singh (Fij) 71 77, George McNeill 72 76, Charl Schwartzel (Rsa) 75 73, DJ Brigman 74 74, Jeff Brehaut 73 75, Tim Clark (Rsa) 72 76, Ben Curtis 71 77, Jose Maria Olazabal (Sp) 70 78, Harrison Frazar 74 74

149 J J Henry 71 78, Ernie Els (Rsa) 73 76, Chris DiMarco 76 73, Ian Poulter (Eng) 72 77, Fred Funk 71 78, Charles Howell III 76 73, John Rollins 75 74, Ken Duke 74 75

150 Jeev Milkha Singh (Ind) 75 75, Michael Campbell (Nzl) 73 77, Zach Johnson 76 74, Kevin Sutherland 74 76, Kenneth Ferrie (Eng) 74 76, Nick O'Hern (Aus) 76 74, Dean Wilson 76 74, Robert Allenby (Aus) 75 75, Camilo Villegas (Col) 73 77, Marcus Fraser (Aus) 72 78, Matthew Goggin (Aus) 77 73, Bob Estes 75 75,Anders Hansen (Den) 71 79, Rory Sabbatini (Rsa) 73 77

Missed cut

151 Kirk Triplett 73 78, Joey Sindelar 73 78, Eric Axley 79 72, Soren Kjeldsen (Den) 76 75, Lucas Glover 71 80, Mark Harrell 75 76, Phil Mickelson 74 77, Joe Durant 75 76, Paul Goydos 78 73, Thomas Bjorn (Den) 75 76, Shaun Micheel 78 73, Tripp Isenhour 74 77, Ryan Moore 78 73, Woody Austin 74 77, Nick Watney 79 72, Johan Edfors 75 76, Luke Donald 74 77, Justin Leonard 75 76, Jon Mills (Can) 73 78

152 Tom Byrum 73 79, Trevor Immelman (Rsa) 73 79, KJ Choi (Kor) 77 75, Jeff Sluman 74 78, Stewart Cink 72 80, Brett Wetterich 77 75, Richie Ramsay (a) 78 74, Vaughan Taylor 74 78, Ryuji Imada (Jap) 74 78

153 Kaname Yokoo (Jpn) 78 75, Sean O'Hair 73 80, Joe Daley 77 76, Padraig Harrington (Irl) 73 80, Nobuhiro Masuda (Jpn) 76 77, Toru Taniguchi (Jpn) 78 75, Retief Goosen (Rsa) 76 77

154 Anthony Wall (Eng) 73 81, Andrew Buckle (Aus) 73 81, Darron Stiles 74 80, Sergio Garcia (Spa) 79 75, Robert Allenby (Aus) 75 79, Arron Oberholser 73 81, Pat Perez 76 78, Warren Pineo 82 72

155 Ricky Barnes 76 79, Chris Stroud 80 75, Davis Love III 75 80, Martin Laird 76 79, Henrik Stenson (Swe) 79 76, Tom Gillis 77 78, Kyle Dobbs 77 78

156 Luke List 77 79, Rodney Pampling (Aus) 81 75, Adam Spiers (Can) 78 78, Darren Fichardt (Rsa) 75 81, Jason Korkrak (a) 76 80, Michael Berg 81 75, Michael Block 79 77, Geoffrey Sisk 77 79, Nathan Green (Aus) 74 82

157 Stephen Marino 79 78, Tim Petrovic 78 79, Rhys Davies (Wal) 74 83, Craig Kanada 72 85

158 Frank Bensel 79 79, Robert Karlsson (Swe) 77 81, Adam Scott (Aus) 76 82, Colin Montgomerie (Sco) 76 82, John Kelly 74 84, Todd Fischer 79 79, Rich Beem 73 85, Lee Williams 80 78, John Koskinen 78 80, Todd Hamilton 81 77,

159 Trip Kuehne (a) 79 80

160 Miguel Rodriguez (Arg) 84 76, Johnson Wagner 77 83, Andy Matthews 79 81, Jeff Golden 82 78

161 Jason Allen 80 81

162 Chris Condello 79 83

163 Christian Cevaer (Fra) 78 85, Martin Ureta 80 83, Alex Prugh 82 81, Steve Elkington (Aus) 84 79, Mike Small 86 77, Philip Pettit (a) 81 82

164 Brett Quigley 78 86

165 Todd Rossetti 78 87

167 Sam Walker (Eng) 78 89, Allen Doyle 81 86

168 Jacob Rodgers 85 83, Ryan Palmer 84 84