An honest caddy cost Rory McIlroy a two shot penalty at the Abu Dhabi HSBC championship in the Middle East on Saturday – but his warning helped the Ulsterman win almost $300,000 on Sunday.

McIlroy finished just one shot behind Spaniard Pablo Larrazabal in the final round as Saturday’s penalty denied him victory on his seasonal bow.

The penalty, for an incorrect drop on the second hole in his third round, only came to light when caddy Dave Renwick informed McIlroy of the infringement before he signed his card.

Renwick, caddying for Ricardo Gozalez, saved McIlroy from the automatic disqualification which would have followed if he had signed for the wrong score.

The caddy waited until the 18th to ensure McIlroy finished the third round with a clear head.

But the two shot penalty ultimately cost McIlroy victory on Sunday on his first outing of the new year as a final round 68 left him tied in second place with Phil Mickelson on 13 under par, one shot behind Larrazabal.

McIlroy admitted: “It’s frustrating - I’ve played the four rounds in one shot less than the rest of the field but I’ve lost the tournament by one shot because of that penalty.

“I should be standing here as the winner but I’m not and it is frustrating because of one incident. I felt I played well the whole week.

“It’s a very positive start to the season so I’m not going to let one little negative ruin that.

“I came in here telling everyone that I’m really happy with my game and done some good work and felt like it was coming together for me at the end of last year. I’ve continued that on, so I’m really excited for the rest of the season.

“I’ve got a week off now to prepare for Dubai and give it another run there and see if I can get the win there.”

It’s the second time in two years that McIlroy has fallen foul of the rules in Abu Dhabi. In 2012 he was penalised two shots in his second round here for brushing away some sand that was not on the green and went on to finish one behind winner Robert Rock.

McIlroy was just as incensed on Saturday when he faced the media after his two shot penalty had been imposed.

He said: “I hit my second shot on the second into the left rough but on the spectator crosswalk. I took a drop and played my shot but I did not notice my left foot was still on the line and you need to take full relief.

“We went out to see it again and see my divot and it was clear I could not have played my shot with my feet anywhere else. It’s unfortunate. If anything it was a disadvantage because I dropped it in a bad lie and did not make birdie.”

But McIlroy had no problem with Renwick bringing the rule break to his attention.

He added: “You have to adhere to the rules of this game and he (Renwick) was pointing out something he thought was questionable. He was just doing what I guess anyone would.”