Phil Mickelson is leading the US Open after Luke Donald dropped shots at 16 and 18 in the conclusion of his first round. 

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.

Mickelson completed an opening three-under 67 yesterday 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 - but his round deteriorated soon after. 

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.

Meanwhile Graeme McDowell is already in big danger of missing the cut at six over.