Teenage rider Donnacha O'Brien has landed a landmark win in the on El Salvador in the Irish Cesarewitch.

The younger brother of Joseph O'Brien, the 16-year-old rode his first winner last month but defied his inexperience with a fine ride on El Salvador trained by his father Aidan and running in the colours of his mother, Anne-Marie.

"I'm delighted and it's great for Donnacha. It's a hard race to win," Aidan O'Brien said.

"He's a tall fellow and is doing his leaving certificate this year. It was a nice, patient ride as the start was a bit messy and he was a long way back.

"He was second in the Queen Alexandra Stakes at Royal Ascot this year, and is a tough horse."

It was a fourth winner for Donnacha O'Brien and a second Irish Cesarewitch for O'Brien after Bright Horizon 2010.