Paul Casey responded instantly to a challenge to his overnight lead in the Alfred Dunhill Links Championship in Scotland today.

Casey led by one shot after an opening 63 at Kingsbarns, one of the three courses used for the £2.6million pro-am event, but was soon overtaken by Wales' Bradley Dredge.

Dredge, whose opening 64 at St Andrews established a new course record for the lengthened lay-out, started with two birdies in a row at Carnoustie and added another on the 14th to move into the lead on 11 under par.

But Ryder Cup hero Casey quickly took advantage of more good conditions at St Andrews to birdie the opening two holes, holing from five feet at the first and 10 at the second.

That drew the 29-year-old Englishman, who can clinch the Order of Merit title this week if he wins here and his main rivals fail to finish high enough, level with Dredge - Sweden's Johan Edfors a shot behind in third on 10 under after eight holes at St Andrews.

Casey is currently £80,000 ahead of David Howell and £250,000 clear of Robert Karlsson on the money list.

But the vast amounts of prize money on offer here and in the season-ending Volvo Masters at Valderrama means Karlsson (third), Henrik Stenson (fourth), Padraig Harrington (fifth) and Colin Montgomerie (seventh) are among those still in with a chance of topping the standings.

Harrington was the best placed of those after an opening 66, while Karlsson and Stenson both returned rounds of 68. Montgomerie - seeking a ninth Order of Merit title - could manage only a 73, while Howell slumped to a 75 as he struggled with a shoulder injury.

Harrington remained six under after three holes today and was joined on that score by Karlsson and Stenson, who had both birdied the sixth and eighth.

Montgomerie three-putted the first to drop back to two over, while Howell bogeyed the second to slump to four over.  PA