Spieth and company are set to start on the first tee at 2.20 p.m. ET (1820 GMT) in Thursday's opening round at Whistling Straits in Kohler, Wisconsin.
Traditionally, the winners of the season's first three majors have always been drawn together.
McIlroy has not officially confirmed his participation in the year's final major, but he will play barring a last-minute setback, and is expected to have a practice round on Saturday.
McIlroy, who won last year's PGA Championship by one shot after a final-round shootout that finished in near darkness at Valhalla in Louisville, Kentucky, has been recovering from an ankle injury.
The 26-year-old Northern Irishman has been out of action since he ruptured a ligament in his left ankle while playing soccer with friends on July 4, but he gave the strongest hint yet earlier on Friday that he would be able to defend his title.
McIlroy, whose injury ruled him out of defending his British Open title last month at St. Andrews, posted a picture of the interior of a private jet with a British passport front and centre on a table.
Accompanying the picture was a series of emojis (or picture characters) indicating a flight from Portugal to the United States followed by a thumbs-up, a victory sign and a golf course symbol.
In other high-profile groupings at Whistling Straits, four-times winner Tiger Woods will play alongside former champions Keegan Bradley and Martin Kaymer for the first two rounds.
American Woods, who clinched the most recent of his titles in 2007, is scheduled to tee off with fellow American Bradley and Germany's Kaymer from the 10th hole at 9:15 a.m. ET (1315 GMT) on the par-72 course at Whistling Straits.
Bradley won his first major title as a PGA Tour rookie at the 2011 PGA Championship in Atlanta while Kaymer triumphed in the year's final major when it was last held at Whistling Straits, in 2010.
Australian world number four Jason Day will set off in the opening round in the company of fifth-ranked Rickie Fowler and his fellow American Dustin Johnson, while England's Paul Casey has been grouped with Americans Bubba Watson and Jim Furyk.
(Editing by Andrew Both)
Share
