With this new four-game window presenting something different for managers across Europe to tackle, a myriad of approaches emerged.

Germany boss Jurgen Klopp named virtually two separate squads for his side’s two pairs of games, while Ukraine made 10 changes between their first two games and then nine for their defeat by Northern Ireland.

Having spoken before the start of the campaign about how the condensed schedule would be more difficult for smaller nations, O’Neill kept changes to a minimum.

He started only different 15 players across the four games with two of his changes enforced by Ballard’s injury and Ethan Galbraith’s absence against Ukraine to attend the birth of his child.

Despite the relatively small pool of starters, this still feels like a window when Northern Ireland’s depth was tested and passed with flying colours.

O’Neill was without talisman Bradley and the reliable Ali McCann coming into the window, and then lost Ballard to a hamstring injury after the first game in Tbilisi.

Young centre-backs McConville, 21, and Tom Atcheson, 20, looked ready to play at this level, while Ciaron Brown started all four games and impressed too having often had to bide his time in past squads.

O’Neill’s praise for his squad was across the board.

“For me it’s been one of the most enjoyable windows I’ve had as an international manager, and that’s been because of the players,” said O’Neill.

“How they’ve applied themselves, how desperate they are to do well, and that’s a real positive.

“We’ve a brilliant group of players and a lot of them I think will play international football for a long time.”