Cycling:FBD Insurance Rás leader Mark Cassidy was involved in a major crash midway through this afternoon's stage forcing him to retire from the race.
Cassidy, who took control of the yellow jersey following yesterday's third stage, fell an hour into the race after heavy rain resulted in a number of crashes throughout today's stage.
The An Post M Donnelly Grant Thornton Sean Kelly team rider hit a rock while racing through Limerick and is believed to have suffered cuts and severe bruising.
In the end it was another Irish rider, 2004 Rás winner David McCann, who ended the day in yellow.
McCann and eleven others forged ahead of the peloton with around 30 kilometres to go in the 156 kilometre stage from Corofin to Tralee.
He finished the stage two seconds ahead of Poland's Wojciech Dybel and Bulgaria's Bogdan Stoytchev.
The race continues tomorrow with a hilly 141 kilometre stage from Tralee to Skibbereen.