Five-time major winner Phil Mickelson has withdrawn from the US Open after good weather ended his slim chances of making a last-minute dash to Erin Hills.
Mickelson needs to win the US Open, in which he has been runner-up a record six times, to complete the career grand slam, but announced earlier this month he would likely miss the event to attend the high-school graduation of his daughter Amanda, who was born the day after he finished second to Payne Stewart at Pinehurst in 1999.
Only a lengthy weather delay - and there had been several already this week - would have given the 46-year-old a chance of being at the ceremony and then flying by private jet from California to Wisconsin.
But when the year's second major championship got under way in perfect conditions on Thursday, Mickelson officially withdrew and left first alternate Roberto Diaz to take his place alongside Stewart Cink and Steve Stricker in a group due to tee off at 2.20pm local time.
Play started on schedule at 6:45am local time with the last three champions, Martin Kaymer, Jordan Spieth and Dustin Johnson, teeing off at 8:35am.
Johnson only arrived at Erin Hills on Tuesday afternoon after fiancee Paulina Gretzky gave birth to the couple's second son - named River Jones Johnson - on Monday, but the world number one is targeting the first successful title defence since Curtis Strange in 1989.
''It's been very fun the last couple of days, obviously having a new son on Monday was awesome,'' Johnson said. ''Everybody's healthy so that's good.
''It actually worked out pretty well that I missed the cut at Memorial, even though I didn't want to. I came up here and got to practice for two days.
''Even though I came in late I didn't feel like I was behind the 8-ball at all because I got to prepare 10 days ago or so."