Young won last month’s Players Championship while fellow American Howell captured last year’s US Amateur at The Olympic Club in San Francisco aged 18.
In other groupings, top-ranked Scottie Scheffler is in the 30th and penultimate group at 5.44am alongside fellow American Gary Woodland and Scotsman Robert MacIntyre.
Two-time Masters winner Scheffler, the reigning PGA Championship and British Open champion, won at LaQuinta earlier this year.
Woodland took an emotional PGA Houston Open victory two weeks ago, his first triumph since the 2019 US Open. Earlier last month, Woodland revealed he still fights anxiety and post-traumatic stress disorder following 2023 brain surgery.
MacIntyre, last year’s US Open runner-up, was second in last week’s Texas Open.
Following ceremonial starters Jack Nicklaus, Gary Player and Tom Watson, are the twosome of American John Keefer and China’s Li Haotong.
Americans Bryson DeChambeau and Xander Schauffele and England’s Matt Fitzpatrick start at 2.07am, with Americans Collin Morikawa and Russell Henley joining Japan’s Hideki Matsuyama 12 minutes later in the group just ahead of McIlroy’s trio.
Other later groups include Spain’s Jon Rahm, Sweden’s Ludvig Aberg and American Chris Gotterup at 5.08am followed by England’s Justin Rose and Americans Brooks Koepka and Jordan Spieth.
- With AFP
