New York - Defending US Open champion Dustin Johnson was grouped with rival Jordan Spieth and Germany's Martin Kaymer in pairings announced for this year's tournament by the United States Golf Association on Thursday.
World number one Johnson will be chasing back-to-back titles when the 117th edition of the tournament tees off next week at Erin Hills Golf Course near Milwaukee, Wisconsin.
His group with 2015 champion Spieth and 2014 winner Kaymer was one of the most intriguing announced by the USGA.
Star power will be on show in another marquee group which comprises three major winners led by former US Open champions Rory McIlroy and Justin Rose.
McIlroy, who declared himself fit for Erin Hills after recovering from a rib and back problem, won the US Open in 2011.
Olympic champion Rose won the 2013 edition of the tournament billed as the toughest test in golf. Rounding out the group is Australia's former world number one Jason Day, winner of the 2015 PGA Championship.
Phil Mickelson, who could complete a career grand slam with a long-sought US Open victory, was given a tee time by the USGA, despite saying last week that he would skip the tournament to attend his daughter Amanda's high school graduation in California.
Mickelson, a six-time runner-up in the US Open, told the New York Times he couldn't envision being able to make a tee time in Wisconsin, but added he wouldn't officially withdraw until a couple of days before the tournament in case some window opened.
Mickelson's tee time of 14:20 wouldn't give him time to get from California to Erin Hills from the graduation ceremony scheduled to start at 12:00, so a weather delay to the tournament might just make his appearance possible.
"If there was any kind of delay, I'll have everything ready to go and we'll hopefully be able to make it," Mickelson said Thursday at the PGA Tour's St. Jude Classic in Memphis. "But it doesn't look too good for that. The weather looks to be pretty nice next week."
Another group sure to attract a following includes a trio of Masters champions, led by Spain's Sergio Garcia, who is paired with Australia's Adam Scott and two-time Augusta champion Bubba Watson.
The next generation of golf stars is reflected in the group spearheaded by big-hitting Spanish star Jon Rahm, who is joined by American Rickie Fowler and Japan's Hideki Matsuyama.
Erin Hills is staging the US Open for the first time. USGA officials have confirmed the yardage for the course will be set at 7 741 yards, potentially making it the longest major championship in history.