Republic of Ireland captain Robbie Keane was disappointed not to be given the opportunity to complete his hat-trick against Northern Ireland.
The Tottenham striker moved within two goals of an international half-century as he netted a brace in the 5-0 win in the Carling Nations Cup in Dublin, but was then substituted.
Stephen Ward and Simon Cox marked their international debuts by both scoring and Northern Ireland's misery was compounded by a Craig Cathcart own goal and a red card for Adam Thompson.
Keane told Sky Sports 1: "It's a friendly game, but when you're playing against your rivals there is no such thing.
"It's always important to get a good win and we did that convincingly.
"I wanted to stay on - I think I need one more to equal the English (goalscoring) record (held by Sir Bobby Charlton), so I was desperate to stay on, but never mind.
"Luckily Coxy stayed on because he scored a goal and it was a great debut for him, we're all delighted for him. All in all, it's a great win for us."
Fellow goalscorer Ward said: "It's nice, obviously to get the win and cap it with a goal, my first goal. It's a good night all round. I enjoyed every minute of it."
Cox added: "I'm pleased. It's a good win for the lads and I capped it off with a nice goal."