With one tournament left to prepare for his bid to complete a career grand slam at next month's Masters, Rory McIlroy says he is disappointed with his form and his “tentative” approach to shots.             

The world number one shot an even-par 72 in the final round of the WGC-Cadillac Championship on Sunday, won by Dustin Johnson, leaving him one-under for the week and well back of the leaders.             

A frustrating week, which included the Northern Irishman's infamous tossing of a three-iron into a pond and in which his ball-striking has been below his standards, ended with a double-bogey at the 18th.             

"The game's just not quite there. I've got a week off now to try and work on it a little bit," said McIlroy, who missed the cut at last week's Honda Classic.             

"I am pretty disappointed with how I played overall. I felt it was a little better again today for the most part but a bit of a disappointing finish. But it's just not quite 100%."             

McIlroy will visit Augusta National next week for a friendly round with his father and Super Bowl winning-quarterback Tom Brady of the New England Patriots before heading to Bay Hill, Orlando, for the 19-22 March Arnold Palmer Invitational, his last scheduled event before the Masters.             

"I've got a week off now to try to work on the game a bit" - Rory McIlroy

Asked whether he had any alarm bells ringing ahead of the 9-12 April Masters, McIlroy was frank: "My inability to hit the ball right-to-left isn't something that you want going into Augusta. It is something I want to try and work on a little bit.             

"Statistically, I hit the ball better. Still it's just not quite as comfortable as I would like.             

"I've got a week off now to try to work on the game a bit and get a little sharper for Bay Hill."             

Having been in such consistently good form in the lead-up to the Honda Classic, McIlroy is having to adjust to his ball-striking being off and says some fear has crept into his game.          

"[I'm] tentative, a little bit scared to play certain shots, because I feel like I can't at the minute. So, hitting away from flags, trying to make sure that I am missing it in the right areas. Just playing quite conservatively, which is very much unlike me," said McIlroy.             

"I have just got to get back at it tomorrow and try to figure out what I need to do."