Marine Nationale (2/1) won the opening day highlight, the Grade 1 William Hill Champion Chase on Tuesday afternoon.
A winner at the Cheltenham Festival last March, the Barry Connell-owned and trained gelding, the son of French Navy ran out a seven-length winner over former Cheltenham Champion Chase winner, Captain Guinness (28/1).
The Rachael Blackmore-ridden runner-up was four and a quarter lengths ahead of Solness (11/1) in third.
Marine Nationale, who won the Champion Chase at Prestbury Park in March, becomes the first horse to complete the 2025 Cheltenham-Punchestown double.
