Tour rookie Streelman is playing in his first US Open
Unheralded Americans Kevin Streelman and Justin Hicks were the surprise leaders after the first round of the 108th US Open at Torrey Pines.
The pair fired three-under 68s to head countrymen Rocco Mediate and Eric Axley and Australian pair Geoff Ogilvy and Stuart Appleby by one stroke.
England's Lee Westwood, Swede Robert Karlsson and South African Ernie Els ended in a group one shot further back.
Tiger Woods shot 72 in his first round for two months following knee surgery.
The world number one, a winner of 13 major titles, last played at the Masters in April when he came second to South African Trevor Immelman.
Woods, 32, showed discomfort at times and admitted to feeling sore after 18 holes but was encouraged by his opening round on the par-71, 7,643-yard Torrey Pines South course near San Diego.
"To make two double bogeys and a three-putt and only be four back, that's a great position to be in because I know I can clean that up tomorrow," he said.
Mickelson and Woods have won nine tour events between them at Torrey Pines
Woods took centre stage and attracted a huge following of both spectators and media in the headline group with world number two Phil Mickelson, who carded 71, and the world's third-ranked player Adam Scott of Australia, who took 73 despite a broken finger.
"Anything around par is kind of your target for the US Open," said local hero Mickelson, who has had to settle for four runner-up finishes in the US Open.
The in-form Westwood was pleased with his round of 70 in the more benign morning conditions.
"I played good solid US Open-style golf," said the 35-year-old. "I hit a lot of fairways and a lot of greens and when I missed I wasn't far off and scrambled well."
England's Luke Donald was in contention at two under after 14 but bogeyed two of his last four holes to slip back to level par.
"It was obviously a little bit disappointing to end with two bogeys but overall it was a good solid start," he said.
Donald's countryman Oliver Wilson, who lost to Spain's Miguel Angel Jimenez in a play-off for the PGA Championship at Wentworth, finished one over, while Ross Fisher ended two over.
But it was a generally disappointing day for the fancied European contingent.
Spain's Sergio Garcia carded 76, Open champion Padraig Harrington of Ireland and English duo Ian Poulter and Nick Dougherty, who led after the first round last year, both took 78, while Paul Casey, Justin Rose and Colin Montgomerie all squeezed inside 80 by one shot.
Also on one under were Australian Robert Allenby and 19-year-old American amateur Rickie Fowler, while Immelman signed for a 75 and defending champion Angel Cabrera of Argentina also amassed a lacklustre 79.
Hicks, a 33-year-old who is playing on the second-tier Nationwide Tour, installed himself as the clubhouse leader early on after seven birdies.
"I know that it's a marathon, not a sprint, and our goal is to keep playing good, steady golf and try to be standing here on Sunday night," said the Michigan native.
Hicks' only other US Open was at Shinnecock Hills in 2004 when he missed the cut but he admitted it had helped to have played in one before.
"We kind of saw what an Open can be like, from the standpoint of being really fast, really firm, really difficult," he said.
"Coming out here, I did a good job of framing in my mind a little bit of kind of what to expect."
Hicks fired six birdies in eight holes on his front nine
Hicks was briefly overtaken in the afternoon by Streelman, a US PGA Tour rookie playing in his first US Open, who then bogeyed the last to drop back into a share of the lead.
"It probably hasn't quite sunk in yet, but it's pretty cool," said the 29-year-old, who tied for 29th at the Buick Invitational at Torrey Pines in January. "I do enjoy this golf course. The lines off the tee kind of suit my eye well."
England's veteran amateur Gary Wolstenholme, 47, who employed BBC 5 Live golf commentator Andrew Cotter as his caddie, carded 83, while 33-year-old US-based Northern Ireland amateur Chris Devlin took 84.
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