Martin O'Neill fielded two entirely different XIs as the Republic of Ireland played out a 0-0 draw with neighbours Northern Ireland in their behind-closed-doors friendly.
The Republic boss rang the changes at half-time at the Aviva Stadium as he attempted to improve match-fitness levels ahead of Sunday's friendly against England and the Euro 2016 qualifier against Scotland which follows it next weekend.
O'Neill told FAI TV: "It was more than useful, it was very good, particularly for some of the players who had not played for quite some considerable time.
"Also, funnily enough, in terms of numbers we were able to change the side at half-time, a completely different side for the second half, which is really what I wanted to do.
"In terms of the opposition, they were very strong and it was great for us. Obviously Northern Ireland have been together for a number of days now - they had the game against Qatar - and they are looking quite strong, so for us it was excellent."
The game gave O'Neill an opportunity to take a closer look at some of his fringe players, and he was delighted in particular to see Bournemouth midfielder Harry Arter at close quarters.
He said: "Of course, I have seen him a lot at club level, but it's nice to see what he is like here in this game. And while there's an element of friendliness about the match, of course it helps, it gives you a better understanding, as it does him as well.
"Also Daryl Murphy has had a really great season for Ipswich. It was nice - he partnered David McGoldrick, who has had very, very little football in the last four months, so all of those type of things were pleasing for us.
"I think the players got some benefit out of it, at least on the physical side."
Northern Ireland face Group F leaders Romania on June 13, the same day on which the Republic welcome Scotland to Dublin in Group D.