Joseph O'Brien's Thermistocles stayed on well at the end of an extended two and a half miles to make a winning debut in a bumper at Roscommon.

The Oscar five-year-old gelding was third racing towards the final furlong as West Burma went for home with Slippery Serpent in second.

However, the petrol wasn't in the tank for West Burma who edged left under pressure and hampered Thermistocles 150 yards out. The latter regained an even keel under Tom Hamilton and galloped on strongly to lead going away inside the final 100 yards.

He hit the line a length and a quarter to the good at 7/2 having been backed down from 6/1.

Slippery Serpent (4/1) chased him home with a three-length gap back to 5/2 favourite West Burma.

Stephen Mahon 's Silverfort was backed from 25/1 in the morning to 13/2 but stumbled and unseated Richie Deegan five furlongs out when on the heels of the leaders.