Phil Mickelson, a five-time runner-up hungry to finally claim the title, seized a one-stroke lead early in Thursday’s first round of the US Open at tough-playing Merion.

Mickelson birdied the par-4 seventh, his 15th hole of the day, to stand on two-under, one stroke ahead of fellow Americans Jerry Kelly and Shawn Stefani, England’s Ian Poulter, South Africa’s George Coetzee, Irish amateur Kevin Phelan and Canadian Mike Weir.

Half the field of 156 had yet to tee off after a morning thunderstorm halted play for more than three and a half hours.

Mickelson skipped practice rounds at Merion on Tuesday and Wednesday to fly across the United States and attend his daughter Amanda’s eighth-grade graduation ceremony, then fly back in time to start the Open on Thursday.

The airplane landed at 4:15 in the morning and the 42-year-old left-hander reached the course 87 minutes later, well ahead of his 7:11 a.m. tee time.

Mickelson is a three-time Masters champion whose only other major victory came at the 2005 PGA Championship. He has finished second at the US Open in 1999, 2002, 2004, 2006 and 2009.

Mickelson teed off at the par-4 11th, used as a starting hole due to course logistics, and opened with a bogey but answered with birdies at the par-3 13th and par-4 first then seized the lead with another at seven.

Some players reached three-under early but Merion’s dense rough has proven formidable to players even after being soaked for the third time in a week, dismissing notions the wet weather would leave the course vulnerable.