Phil Mickelson defied a lack of sleep to set a tough early target in difficult conditions on the storm-hit first day of the 113th US Open.
The left-hander attended his daughter's graduation in San Diego on Wednesday evening before flying to Philadelphia, landing at 4.15am and heading straight to Merion to prepare for his 7.11am tee time.
But the four-time major winner, perhaps aided by a three-and-a-half hour delay for thunderstorms, carded a solid three-under 67 - his best opening round in the event since 1999.
Mickelson started with a three-putt bogey at the 11th but clawed the shot back at 13 before he was given the chance to rest up when the approaching storms forced the players back to the clubhouse.
The respite clearly had a positive effect on his game as he got under the card with a birdie at the first, and he nailed further birdie putts at the seventh and ninth to hit the top until Luke Donald surpassed him with the final putt of the day.
"I loved having an early tee time," said Mickelson, who hit 11 of 14 fairways and 14 greens in regulation.
"I wish we did not have the delay because it made it a long day but the golf course is playing about as easy as it could, but Merion is fighting hard.
"It's one of the best I've seen for a US Open. It's soft but we are having a hard time getting under par."
Asked about preparing at home rather than at Merion, he added: "When I was here (Merion) the week before I was able to do all the work I needed.
"The last part was getting my game sharp so being able to do that in nice weather on a good practice facility was advantageous."
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