Phil Mickelson needed a birdie on the 18th green Friday to join Billy Horschel atop the leaderboard with the second round of the U.S. Open suspended due to darkness.
Mickelson was the leader when the first round was completed earlier Friday. He opened with a 67, but carded a 2-over 72 in round two to dip to 1-under-par 139 after 36 holes.
He was joined there by Horschel, who fired a 67 in round two to grab a share of the lead. Horschel put together a second round in which he hit all 18 greens in regulation.
Luke Donald (72), Justin Rose (69) and Steve Stricker (69) finished at even- par 140. Ian Poulter and amateur Cheng Tsung Pan were also at even-par, but have four and nine holes remaining, respectively.
John Senden (71) and Nicolas Colsaerts (72) finished two rounds at 1-over-par 141, while Mathew Goggin is the only one done at 2-over 142 after a second- round 74.
Tiger Woods and Rory McIlroy are among those tied at 3-over 143. The duo was paired together for the first two rounds, and posted matching rounds of 73-70.
They finished both rounds on Friday as there were a pair of weather delays on Thursday. Second-round action was suspended for the night Friday due to darkness. The round will resume on Saturday morning at 7:15 a.m. ET.
Among those unlikely to make it to the weekend are Zach Johnson, David Toms, Graeme McDowell, Darren Clarke, Angel Cabrera and local favorite Jim Furyk.
Woods opened the second round on the 11th tee and he parred his opening two holes. After making birdie at the short par-3 13th, Woods tripped to a bogey at the 14th.
He made bogey at the 18th as he headed to the front side at plus-4. He got two strokes back with birdies on Nos. 2 and 4, both par-5s. After a pair of pars, he pulled his approach left of the seventh green.
He flubbed his chip shot, then got up and down for bogey to slip to plus-3. Woods parred his final three holes to end there.
"I played well. I just made a couple of mistakes out there today, but I really played well," Woods stated. "Maybe I could have gotten one or two more out of it, but it was a pretty good day."
McIlory got off to a flying start in the second round as he birdied the 11th and 12th to move to plus-1. He faltered to a bogey at the 14th before making four pars in a row.
The 2011 champion at Congressional bogeyed the first. After a birdie on the long par-3 third, McIlroy gave that stroke right back as he bogeyed the par-5 fourth.
McIlroy again traded a birdie for a bogey at eight and nine. He parred the 10th, his last, to end alongside Woods at plus-3.
"The pins were a little tougher, for sure. They put the pins in places that even when you hit it close, you had a tough putt for your birdie or your par or whatever," said McIlroy. "And the wind is obviously up. And it's tough to gauge this wind. It swirls a little bit in these big trees and it's hard to pull a club sometimes. So that's why I think you're seeing the scores rise a little bit today. Hopefully rise a little bit more in the afternoon."
With Horschel already finished at 1-under, Mickelson started his second round with a bogey at the first. He ran off 10 consecutive pars from the second.
Mickelson's short par putt at the 12th spun out as he dropped to minus-1 with the bogey. At the 13th, his tee ball flew the green into the back bunker. His blast from the sand nearly found the bottom of the cup, but he walked off with another bogey as he missed another short par effort.
The five-time U.S. Open runner-up parred his next four holes, before rolling in a birdie effort from about 15 feet out at the last.
"It felt great. I wasn't expecting birdie there. It's a very difficult hole," Mickelson said. "I played really well. Even though I shot 2-over, it was the birdie opportunities that I didn't capitalize on. Had I made one on No. 2 or that birdie on eight or nine or 11, I would have changed kind of the momentum of the round. I played well today even though I didn't feel the score was what I thought it should be."
Horschel birdied the par-5 second to get his round going. He ran off seven straight pars from there.
The Zurich Classic winner converted back-to-back birdie chances at 10 and 11 to move to minus-1 for the championship.
After a par at 12, Horschel 3-putted for bogey on the short, par-3 13th. He atoned for that mistake with one of the seven birdies in round two on the par-4 18th to end at 1-under par.
"I liked it better where I could play one round and go right into the next round instead of playing Thursday and wait all day today and get nine holes in," Horschel stated. "I feel better when I play more and more holes. I feel more comfortable and get better rhythm."
NOTES: Horschel's only other major championship was the 2006 U.S. Open at Winged Foot, where Mickelson lost the lead on the 72nd hole ... The projected cut line is hovering at 7- or 8-over par ... If it remains at plus-7, among others that would miss that cut would be Martin Kaymer, Dustin Johnson and Brandt Snedeker.