Strongman Padraig Harrington romped to a five-shot win in the Dunhill Links Championship and blew the Order of Merit race wide open.

The Dubliner cruised to his first win for 15 months by the biggest winning margin of his career to throw down the gauntlet to money leader Paul Casey.

Harrington birdied the 18th at St Andrews to card a brilliant, bogey free 68 and to finish out of sight on 16 under par.

Four years after winning the title in sudden-death, Harrington did it is style this time to boost his chances of becoming European No1 for the first time.

A cheque for €630,566 moved him from fifth to second place in the race for the Order of Merit title with just two events remaining.

He beamed: "The Order of Merit is a big deal - a huge deal. This time of the year everything is about the Order of Merit. It gets you going again and it is something that you want to put on your CV, definitely.

"I've been using it as motivation after the Ryder Cup to get out on the golf course and push on.

"It is always special to win at St Andrews, and Carnoustie and Kingsbarns. These are great golf courses and while I won here four years ago it was a little tighter then and this was the first time I could walk down 18 and enjoy it. It's very special.

"I haven't won in Europe for two years. I had a couple of wins in the States but it is been 15 months now and it is is really special to win.

"I am very happy at the way I did it. I played great yesterday and I backed it up again today."

Harrington started the day one stroke behind Welshman Dredge but wiped out that deficit with a birdie on the first.

Dredge went back in front with a birdie on the fifth but Harrington pegged him back again on the ninth.

The key hole was the 11th however, which saw a three-shot swing in the Irishman's favour.

Dredge found Strath bunker off the tee and was forced to play out backwards on his way to a double-bogey five, while Harrington holed from 10 feet for a birdie two.

That allowed Harrington to cruise to his second victory in the event in four years, and he also helped partner JP McManus to win the team competition for the second time as well.

With the Order of Merit in his grasp, Harrington has decided to book his ticket to the Mallorca Classic in two weeks' time and close the gap on Casey, who is taking two weeks off before the season ending Volvo Masters.

Harrington said: "To be honest Valderrama has not been the happiest hunting ground for me. I will do well there to finish in the top ten. So anything in Mallorca that can push me on a little bit is welcome. It looks like I'll be there."

Harrington and McManus closed with a ten under par 62 to win the team event by five shots from Angel Cabrera and his son Federico on 35 under.

And Harrington paid tribute to his amateur partner, adding: "All week it's been very good. It was a big bonus to me in the second day at St Andrews because I was losing my patience in the middle of the round and the team actually kept me going.

"JP made a couple of birdies and that sort of pushed me on a bit. It definitely helped. It was an easy time to go backwards and instead I stayed focussed on the team and through that period."

Casey finished tied for sixth on nine under par after a closing 68 but confessed that he is too tired to add Mallorca to his schedule and will take his chances against Harrington and third placed David Howell in the Volvo Masters.

Casey said: "I am not going to change the routine. I really need two weeks off. The past four weeks have been fantastic. But they are very draining at the same time. I have played some wonderful golf but they are very draining and I am absolutely cooked.'

Meath's Damien McGrane finished tied for 15th on seven under after a 69 and earned €49,292 to move into a Volvo Masters berth at 53rd in the money list.