Front-running again reaped benefits as Porthaw claimed the Fethard Maiden at Clonmel under Gary Carroll.
The Paul Magnier-trained son of Invincible Spirit proved game, sticking his head out down the straight as a wall of challengers tried to pass.
He got home by three-parts-of-a-length from Chic Shanique with Celestial Prospect a neck back in third.
The five-year-old began his career with three uninspiring efforts over hurdles but had shown promise switched to the level at Naas last time.
"I hope the handicapper is kind as it was a poor maiden," said Magnier afterwards.
"He's a progressive type of horse and we'll find his level over a mile-and-a-half.
"He's unusual for an Invincible Spirit in that all he does is stay."
