It was the first round McIlroy has played since his official job with coach Pete Cowen was announced
Rory McIlroy found a swimming pool at a tee in his first group game at WGC Matchplay in Texas en route to a 6 & 5 loss to Ian Poulter.
The four-time main winner’s erratic drive on Austin’s fifth hole was one of several mistakes made during his defeat.
The Northern Irishman who now has coaches Pete Cowen on his team, also found water on 13 with a chip over the green as Poulter sealed the win.
The 31-year-old will face the American Lanto Griffin in his next group game.
His last competition will be against the Australian Cameron Smith, who finished second at last year’s Masters.
The 64 players in Austin are divided into 16 groups of four, with only the group winners reaching the knockout round at the weekend.
Other notable games on the first day include the All-England game between Tyrrell Hatton and Matt Wallace and Lee Westwood against Ryder Cup teammate and 2017 Masters champion Sergio Garcia.