Americans Jim Furyk and John Cook, South Africa's Rory Sabbatini and Peter Hanson, of Sweden, are the only players to break par in a star-studded field

The leaders all posted one under par rounds of 71 on the testing 7,453 yard lay-out in windy conditions.

World number one Tiger Woods returned a 79, for +7, with his only birdie of the day coming at the 17th hole.

Woods attracted an enormous gallery of spectators throughout the day, estimated to be close on 10,000 at times.

Best of the Irish at the end of a thrilling day's action which drew close a record crowd of more than 40,000, was Rory McIlroy at even par.

Defending champion Padraig Harrington returned a 76 to leave him on +4.

The team event is being led by Limerick golf enthusiasts Neal Whelan and Gary Neville as well as Cian Foley, son-in-law of Pro Am host JP McManus.

Whelan, a member of Rathbane Golf Club, Neville, who is attached to Adare Golf Club and Foley, who plays out of Dooks Golf Club, combined superbly with their professional Camilo Villegas, of Columbia, to return a stunning score of -17.

The trio enjoy a one-shot advantage on their nearest rivals. The second-placed team features three members of the McManus family, Gerry, Mark and Cormac.