Firm and fast conditions are expected for the field of 91 at Augusta National, where McIlroy will try to become only the fourth back-to-back green jacket winner after Nicklaus, Nick Faldo and Tiger Woods.
Golf's elder icons drew applause from a crowd gathered near the first tee in the early morning light for the honorary starters.
Nicklaus, 86, won six of his record 18 major titles at the Masters while 90-year-old South African Player captured three of his nine majors at Augusta National and Watson, 76, took two Masters titles and five British Opens among his eight major wins.
Second-ranked McIlroy, a five-time major winner from Northern Ireland, tees off in the first round at 10:31 a.m. (1431 GMT) alongside Americans Cameron Young, the world number three who won last month's Players Championship, and Mason Howell, last year's US Amateur winner.
World number one Scottie Scheffler, a four-time major champion, launches his quest for a third Masters crown in five seasons at 1:44 p.m. in the penultimate group alongside fellow American Gary Woodland and Scotsman Robert MacIntyre.
Conditions are expected to produce a hard surface with lightning-fast greens where approach shots will struggle to stay in position.
Other expected challengers for the title include LIV Golf stars Jon Rahm and Bryson DeChambeau, both two-time major champions.
American Xander Schauffele and England's Matt Fitzpatrick are among other past major winners expected to contend, while a host of golfers seeking their first major victory include Sweden's Ludvig Aberg and England's Tommy Fleetwood.