Luke Donald was left to rue a poor finish as the delayed first round of the 113th US Open resumed on a cold, overcast morning at Merion today.
Donald birdied the 11th, 12th and 13th before play was suspended for the day due to darkness on Thursday evening after two delays for bad weather totalling more than four and a quarter hours.
That gave the world number six a one-shot lead over five-time US Open runner-up Phil Mickelson, who had completed an opening 67 to set the clubhouse target, with Belgium's Nicolas Colsaerts (69) the only other player to complete a sub-par round.
Play resumed at 7:13am this morning and Donald parred the difficult 14th and 15th - holes where Sergio Garcia hit consecutive drives out of bounds to run up a six and an eight respectively - to remain four under.
But the 35-year-old then three-putted the 16th and 18th - he also badly misread a birdie putt on the 17th - to card a two-under par 68 before a quick turnaround ahead of the second round.
"There was a complete switch in wind and obviously a big drop in temperature (from yesterday)," Donald said.
"It meant 14 and 15 are playing long but it sort of made 16 and 18 easier and that's why it's a little disappointing to come off those two holes making bogey, despite hitting the greens.
"I'll grab something quick to eat, hit a few balls and get out there. I think it's good to have a quick turnaround, I'll still be warm."
Playing partner Lee Westwood had resumed on one under after a double bogey on the 12th yesterday when his third shot to the par-four 12th clattered into one of the wicker baskets used instead of a standard flag and rebounded back off the front of the green.
He bogeyed the 17th on his way to a level-par 70 and then offered a typically sardonic response when asked about the incident.
R&A chief executive Peter Dawson was the rules official with his group and Westwood said: "Peter Dawson has assured me we will be going back to flags for the Open Championship, like normal people."
The marquee group of Tiger Woods, Rory McIlroy and Adam Scott - the world's top three - failed to live up to expectations, Woods and McIlroy both shooting 73 and Scott a 72.
McIlroy bogeyed three of the last four holes this morning while Scott played the last seven holes in five over, including a double-bogey six on the 15th where he hooked his drive out of bounds and was only a few feet away from doing it a second time.
Woods had winced in pain from his left arm on several shots out of the rough but said: "It is what it is and you move on and I've got to get ready for this next round in a little bit.
"It's one of those golf courses where there's some easy holes and there's some hard holes that follow.
"You've got to take care of the easy holes and try and get through the hard ones and for some reason I left myself quite a few putts in there where they were easily makeable and I didn't make any."
Only five players were under par when the first round was eventually completed, Mickelson leading by one from Donald and Australian Mathew Goggin with Colsaerts and Florida-based Scot Russell Knox a shot further back.
Knox, who attended Jacksonville University and sealed his place at Merion through sectional qualifying, said: "I'm thrilled. I didn't really know what to expect in my first major, but I knew I was capable of having a nice round and made some nice putts and hung in there. It's hard though.
"It's tough, but I'm definitely not in a position to complain. My first major, I'm just thrilled to be here and so you won't hear any complaining out of me."
The second round was already under way and Donald holed from 20ft for birdie on the 12th and chipped in from behind the 13th green for another to take the outright lead on four under, with Mickelson not due out until 3:41pm local time.