Luke Donald, Rory McIlroy and Lee Westwood at Doral this year. Photo Eoin Clarke/www.golffile.ie Rory McIlroy will regain the world No 1 ranking from Luke Donald tomorrow after the Englishman failed to clinch a top-eight finish at the RBC Heritage in South Carolina.

“#1 again without touching a golf club this week…. I wish it was that easy!” McIlroy wrote on Twitter.

“Not my best week, getting used to leaving this place ranked #2,” Donald tweeted afterwards, referring to the play-off loss at Harbour Town Golf Links last year that cost him the chance to become world No 1 for the first time. “Nice week off now.”

McIlroy’s former stablemate Lee Westwood was one of the first to reply to Donald, tweeting: “You’re such a loser Luke! You let me down!”

Donald closed with a level par 71 to finished tied 37th place on two over par as Carl Pettersson closed with a 69 to win by five strokes from Zach Johnson on 14 under par.

Ron Green Jnr of the Charlotte Observer reported on his blog that Donald was more worried about improving this short game than losing the No 1 spot:

“Is it a concern? No,” Donald said. “Obviously, I would have liked to have played a bit more consistently this year. I built up a nice lead last year through some good tournaments and winning a bunch and being consistent. This year hasn’t been quite as consistent. As a result, there’s a little bit of fluctuation in the world rankings now. So, nothing too worried about.” Donald held the No. 1 spot for 40 weeks, lost it to McIlroy for two weeks then held it four more weeks after his victory in the Transitions Championship. “I didn’t have it just for a few weeks,” Donald said. “I had it for something like 40 or 45 weeks, so I’ve experienced it and enjoyed it and hopefully I can get it back again. It’s never really been the focus. Obviously, there was a lot more focus the first time around, trying to get to No. 1. Now my focus is solely on trying to win tournaments and win majors.”.

McIlroy, who is taking a three week break before reappearing in the Wells Fargo Championship in three weeks, held the No 1 spot for two weeks before Donald regained it by winning the Transitions Championship in a play-off  four weeks ago.

Donald had a chance to become world No 1 for the first time in last year’s RBC Heritage but lost in a play-off with Brandt Snedeker.

He eventually took over from Lee Westwood at Wentworth few weeks later when he beat his Ryder Cup team mate in sudden death to claim the BMW PGA Championship.

He went on to remain as No1 for 40 weeks before McIlroy became Irish golf’s first No 1 with victory in last month’s Honda Classic in Florida.

Donald won four times last year to become the first player to win the officials money titles in Europe and the US.

He admitted that getting to world No 1 was a big goal the first time around but added earlier this year: “Now my focus is on winning tournaments.”

Donald will not play alongside McIlroy in the Wells Fargo Championship but plans to return to action in the Zurich Classic of New Orleans from April 26 where defending champion Bubba Watson will make his first PGA Tour appearance since winning the Masters.