Stephen Peters hit a composed century and Monty Panesar picked up three wickets as Northants cruised to an eight-wicket victory over Ireland.
West Indies import Ravi Rampaul failed to provide the catalyst for a surprise win, as he took 1-50 in 10 overs after the Irish batsmen had made 203-9.
Paul Stirling, aged 17, hit four sixes in his promising innings of 70 for Ireland, but his team-mates failed.
Panesar, one of seven Northants bowlers, took 3-36 in nine overs.
One of the most significant contributions came from Irishman Niall O'Brien.
He returned to haunt his former team-mates with a career-best one-day score of 75 as he and Peters put on 179 for the first wicket, putting the result beyond doubt.
