Belief that Northern Ireland could seal second spot ahead of Slovakia surged after they were comfortably the superior team when these sides met in Belfast last month, winning 2-0 with a performance that the side’s record goalscorer David Healy said was perhaps their best ever under O’Neill.
In the weeks since, however, there is a growing feeling that tables have turned somewhat.
Slovakia were missing influential pair Stanislav Lobotka and David Hancko for the game at Windsor Park with both expected to be back in Francesco Calzona’s starting line-up at the Kosice Football Arena this time around.
Northern Ireland, however, will be without three-quarters of the midfield that so impressed in the reverse fixture with Shea Charles and Ali McCann injured, while Ethan Galbraith is suspended.
How the manager fills such considerable holes in his line-up has been the key talking point since his squad was confirmed last week.
In Napoli’s Lobotka, O’Neill believes Slovakia can again call upon one of the best defensive midfielders in Europe.
“He’s an excellent player and he plays at the top level of the game with Napoli, but we look at Slovakia as a team, we don’t look at them as one player or two players,” he said.
“It won’t change the way Slovakia try and play. We have to deal with that as a team, it’s not one individual player.
“We don’t envisage any dramatic change in their strategy or how they look to play tactically, but they’ll obviously be stronger.”