Rory McIlroy's attempt to find some form ahead of next week's Masters hit the buffers as he carded a level-par 72 in the Texas Open.
McIlroy only added the event to his schedule at the 11th hour after struggling to adapt to new equipment and recapture the form which brought him five wins in 2012, including a second major at the US PGA Championship.
Starting from the 10th on the tricky Oaks Course - the fourth most difficult on the PGA Tour last year - McIlroy opened with four pars before picking up a birdie on the par-five 14th and another on the 17th.
However, a bogey on the 18th was the first of three in succession which dropped him back to one over par, not what the world number two was looking for after speaking of the need to cut out "silly mistakes" in his rounds.
The 23-year-old stopped the rot with pars at the third and fourth and then birdied the next two holes, but carded his fourth bogey of the day on the ninth and had to settle for an opening 72.
"More mental than anything else," McIlroy said. "It's just about limiting those mistakes. It's definitely more mental mistakes than physical."
At level par, McIlroy was four shots off the early clubhouse target set by another multiple major winner, Ireland's Padraig Harrington returning a 68 marred only by a bogey on the 18th.
Only two players have won the week prior to the Masters and then gone on to win in Augusta: Sandy Lyle in the Greater Greensboro Open in 1988 and Phil Mickelson in the BellSouth Classic in 2006.