Second-round Leaderboard-1 J Furyk (US), T Woods (US), D Toms (US)+1 J Peterson (US), N Colsaerts (Bel)Others: +4 J Rose (Eng), E Els (SA), S Garcia (Spa) +5 L Westwood (Eng), I Poulter (Eng)+7 P Mickelson (US)+9 M Laird (Sco), B Watson (US)SAN FRANCISCO - Tiger Woods maintained his first-round momentum to share the halfway lead with fellow Americans Jim Furyk and David Toms in the US Open at Olympic.Woods, bidding for a 15th major title, shot 70, while 2003 champion Furyk took 69 and 2001 US PGA winner Toms carded 70 to lead by one at one under par.Graeme McDowell, the 2010 champion, was one over with Nicolas Colsaerts, John Peterson and Michael Thompson. Holder Rory McIlroy and world number one Luke Donald missed the cut.The world’s two top-ranked players were unable to fight back after disappointing first rounds and carded 73 and 72 to end 10 over and 11 over respectively.McIlroy said: "It’s just such a demanding golf course and punishes the slightest shot that’s off-line or that’s maybe not the right distance.”Five-time runner-up Phil Mickelson took 71 to end seven over, but Masters champion Bubba Watson also fell foul of the eight over cut mark with 78, 71 for nine over.The 36-year-old Woods, three shots adrift of leader Michael Thompson in tied second overnight, picked up a shot at the third to take the lead but went backwards with three straight bogeys from the fifth.But he settled himself with two pars before further birdies came at 10 and 13, and he missed other decent chances, notably on the 17th."It was really, really tough and I just had to stay as patient as possible,” said Woods. "I think I’m in a good spot. This tournament, you just keep plodding along.Woods’s last major triumph came at the 2008 US Open before turmoil in his private life, injury and changing to a new coach derailed his progress. But eight times out of nine when he has held at least a share of the lead after 36 holes at a major he has gone on to win.