Justin Leonard shot a first-round 65 to finish day one in a four-way tie for the lead at the OHL Classic of Mayakoba.
The 43-year-old fired six birdies in a bogey-free round as he finished up on six-under-par, alongside Aaron Baddeley, Shawn Stefani and Derek Fathauer.
The quartet are being closely tracked by Michael Thompson, DJ Trahan, Charles Howell III and Patton Kizzire, who all carded 66 on Thursday to end up one stroke behind.
Northern Ireland's Graeme McDowell is one of 14 players two shots off the pace on four-under, with one of those - Hunter Stewart - failing to finish his session after fading light cut short a promising first round on 15.
His playing partner Dawie van der Walt, who sits on three-under, finished up on the 15th, while Si Woo Kim - who also had carded 68 - will resume on 16 tomorrow.
