Graeme McDowell's defence starts poorly ay OHL Classic in Mexico
Graeme McDowell's defence of the OHL Classic appeared to be in tatters after a disappointing opening round in Mexico.
The Northern Irishman, who won a three-man play-off last year, carded a four-over-par 75 which included one birdie and five bogeys, leaving him 12 shots off the pace.
Former world number one Luke Donald matched McDowell's poor round while fellow Englishman Ian Poulter was one over.
American Chris Kirk moved into the outright lead after recording eight birdies, including three in a row from the 13th, in his 63.
Kirk, a four-time PGA Tour winner, was one shot clear of a chasing pack consisting of Americans Gary Woodland and Ben Crane plus Colombian Camilo Villegas.
Webb Simpson, who has only won once in 102 starts since his 2012 US Open triumph, Aaron Wise, Scott Piercy, Kevin Streelman, Nicholas Lindheim and Abraham Ancer were one shot further back.
Wise produced the moment of the day, making a hole-in-one on the par-three fourth, before following it up with an eagle on the next.
Kirk's lead at the top was threatened when Ancer collected five birdies in eight holes, including three in a row early on the back nine, only for the Italian to suffer his only blemish on the final hole when a bogey derailed his charge.
Ireland's Seamus Power, a PGA Tour rookie, and Scots Martin Laird and Russell Knox were locked on three under.