(CNN) -- Rory McIlroy says he needs to cut out his "stupid mistakes" if he is rediscover his form ahead of the Masters at Augusta in two weeks' time.
The 23-year-old lost the world no.1 spot to Tiger Woods this week and is still searching for his first tournament win in 2013
Woods, a 14-time major winner, climbed back to the top of the rankings with victory at the Arnold Palmer Invitational at Bay Hill, Florida on Sunday.
In a friendly text message, the American challenged McIlroy to respond at the Houston Open tournament which began on Thursday at the Redstone Golf Club, Texas.
But it was a difficult first round for McIlory who carded a one-over-par round of 73 to leave him in danger of missing the cut unless he improves over the next 18 holes.
The 2012 PGA Champion bogeyed the par-four second before needing seven strokes to sink the par-five eighth hole.
"Stupid mistakes, silly bogeys"
The back nine was a happier hunting ground for McIlory as he mixed four birdies with two bogeys but when he was asked in Houston what he needed to do to improve he said: "I'm not too sure.
"I think if I just eliminate the stupid mistakes and the silly bogeys then I feel like I'm playing OK and hitting the ball well."
McIlroy's slump in form has been linked to his switch to Nike equipment this year in a deal reported to be worth $250m.
The 23-year-old indicated that he was still not comfortable with his competitive game.
"I'm still maybe a bit tentative out there on the golf course," he added. "I'm not committing to my shots fully.
"Hopefully another three rounds this weekend and some good scores will give me confidence going into the Masters."
American D.A Points held a one-shot lead over compatriots Cameron Tringale and John Rollins after finishing on eight under for the day in Houston.
Points revealed he was using a refurbished version of his Mom's putter that he had borrowed from her golf bag when he was a teenager.