The American shot a bogey-free six-under par 64 that left him three shots behind Varner
The 44-year-old hasn't featured in any PGA tour event since mid-February
He jumped to the top of the leaderboard behind a run of four straight birdies from the fourth and another at his last for a four-under 66 and get to 11-under for the tournament
The Englishman waltzed into the first-round clubhouse lead with a bogey-free seven-under-par 63 that left him one shot clear of Venezuela's Jhonattan Vegas
At 8:46 a.m, the horns sounded three times at stately Colonial Country Club in Fort Worth, Texas and across the sun-kissed layout players stopped in their tracks to honour George Floyd
McIlroy also lauded the PGA Tour for putting in place strong protocols in the wake of Covid-19 pandemic
It will be observed during the 8:46 a.m tee time during each round