O'Neill added: "We've put ourselves in a position where we have to win the game and Wales probably the same".
Wales have now scored one goal more than Croatia, but if Croatiadraw and score one goal more than Wales - e.g. if Walesdraw 0-0 and Croatiadraw 1-1, or if Walesdraw 1-1 and Croatiadraw 2-2 etc. - then their records will be identical.
Elsewhere in Group E, Denmark were held 1-1 by Romania in Copenhagen after Ciprian Deac's late header cancelled out Christian Eriksen's second-half penalty, but the point was enough to secure the Dane's play-off place.
As it stands, Wales' total (-17) is four points worse off than Croatia's (-13).
He assumes more of an attacking role for Wales, given license to roam as opposed to the withdrawn role he often plays in the holding two at club level, where Arsene Wenger is spoilt for choice in attack with Mesut Ozil and Alexis Sanchez to call upon.
"It was between us and Wales for the last place in Pot five and six". A coin toss, essentially.
Noel King has challenged the Republic of Ireland U21s to continue an unbeaten start to their European Championship qualifying campaign by ending Israel's. I spent so much time in Ireland and I've still got family in Dublin.
Martin O'Neill (Republic of Ireland): "I think we can win the match".
Giampiero Ventura's misfiring Italy limped into the uncertainty of the qualifying playoffs.
Iceland is a clear favourite when it hosts Kosovo in its last qualifier, while Croatia has to travel to Ukraine for a tough encounter.
Iowa State Beat Oklahoma as a 31-Point Underdog
The touchdown came after Kansas State's Matthew McCrane missed a 53-yard field goal attempt that bounced off the left upright. With a huge non-conference win under their belt, the Sooners looked to be a real contender for the College Football Playoff .
Gareth Southgate leads England through to 2018 World Cup
Gareth Southgate wants to prepare for the World Cup with a series of home friendlies in different stadiums across the country. Jack Butland and Jesse Lingard could be in the England team for the game in Lithuania on Sunday.