Padraig Harrington made a sizzling start in the Dunhill Championship but still lost ground to red-hot Paul Casey.

The Dubliner opened with a six under par 66 at Kingsbarns only to discover that Order of Merit leader Casey had just carded an incredible 63 in the group in front.

Harrington trails Casey by over €750,000 in the race to be European No 1 this season and faces an uphill battle now after Casey's incredible start.

Harrington said: "It was a great start with four birdies in succession and nice to be four under after four and then nice also to birdie the last.

"I got off to a good start last week in the American Express but I was then very tired over the weekend and I will be wary that doesn't happen again this week.

"So I won't be overdoing this week and it was obvious last week, apart from Tiger, that a lot of the guys in the mix like Adam Scott, Ian Poulter and Ernie Els were not involved in the Ryder Cup. But a 66 is a good start and I'm not too far behind Paul."

Ryder Cup star Casey had seven birdies and an eagle two in a nine under par effort to lead the pro-celebrity event by a stroke from Swede Johan Edfors and Welshman Bradley Dredge.

Casey said: "I am quite surprised with the nine under. Last week I was quite tired and didn't have anything left to give and struggled a little but. But this was very refreshing to go out there to make lots of birdies and an eagle."

The eagle came at the par four sixth, where he holed a wedge from 80 yards just two weeks after he made a hole-in-one in the Ryder Cup at the K Club.

Casey explained: "It was tough hole today because we couldn't carry the bunkers. I got lucky to avoid bunker down left, had 80 yards left and if I could just get it over the right, which is exactly what I did, it would run down the pin and fortunately it went in the hole. Nice to have a a couple of hole outs over the last few weeks."

Casey, 29, finished the day 12 shots ahead of his nearest rival at the top of the money list, Ryder Cup team-mate David Howell, who struggled to a 75 after suffering a recurrence of a shoulder injury.

But the current European No 1 confessed that he is not putting too much pressure on himself to win the Order of Merit after an outstanding year.

He said: "I'm really not going to think about it. I would dearly love to win it and if it happens, it happens, but if it doesn't, it doesn't.

"But it would be a wonderful honour. I have achieved so many of my goals this year and feel very satisfied so, if I was to win, it would be brilliant. If not, then it doesn't matter as I've had a wonderful year anyway.

"I can't control what the other guys do. I have David behind me and a few other guys are very much in it.

"Padraig Harrington asked me this morning if I was playing in Mallorca before Valderrama but I'm not going to change my schedule. I am tired and I need a break."

Casey is €120,000 ahead of Howell and €370,000 clear of Robert Karlsson in the Order of Merit race with Henrik Stenson, Harrington and Colin Montgomerie also in with a shout of overtaking him.

Harrington was the best placed of the chasing pack on six under par with Karlsson and Stenson two shots further back.

Playing partner JP McManus improved their team score by two shots but their eight under par total still left them two adrift of joint leaders Dermot Desmond and Robert Karlsson.

Paul McGinley chiselled out a one under par 71 at Kingsbarns, two- putting the par five ninth from just short of the green for a closing birdie alongside actor Kyle MacLachlan.

The Ryder Cup hero also cleared up some confusion over his defence of the Volvo Masters title later this month.

Fearing he could miss out as he is not inside the top 60 on the money list, McGinley has since learnt from the European Tour that the defending champion is now guaranteed a place in the field.

Graeme McDowell and Damien McGrane. who also look certain to be at Valderrama, opened with one under par rounds of 70 at Carnoustie with Peter Lawrie posting an even par 71

But it was a bad day for Gary Murphy, who needs a couple of good weeks to guarantee his tour card next year.

The touring professional for the Heritage had an expensive bogey- double bogey finish to his round at Carnoustie and ended up with a one over par 72

Murphy is 117th in the Order of Merit with the top 115 retaining their cards but he is odds on to avoid the Qualifying School, unlike Belfast's Michael Hoey.

At 194th in the money list, the former Amateur champion is more than €150,000 away from salvation and will do well to earn that this week after a disappointing level par 72 at St Andrews.

Two under par after just two holes, Hoey bogeyed the third and fifth but birdied the eighth to turn in 35.

But despite getting back to two under with another birdie at the 12th, he bogeyed the 15th and Road Hole 17th to finish the day in the middle of the pack.