England slipped to 10th, swapping places with Chile, while Wales retained their position of ninth to go above the Three Lions for the first time in their history.
Chris Coleman's men top Group B in Euro 2016 qualifying and two victories in the next four days will secure their place at the finals for what would be their first major tournament appearance for 58 years.
Coleman himself appeared unfazed by the rankings shift, saying on Wednesday: "The rankings won't get us to France. I wish it would but they won't."
England top Group E, having won all six games, and are already guaranteed of at least a play-off place but will book their spot in France if they beat San Marino and Slovenia fail to defeat Switzerland this weekend.
Argentina retained the number one ranking, while Belgium, behind Wales in their qualifying group, stayed in second with Germany third.
Scotland have moved up to 32nd and Northern Ireland and the Republic of Ireland have both fallen a place, to 41st and 51st respectively.
Asked about the new rankings, and the fact that the Republic of Ireland had beaten Wales, Scotland and Northern Ireland in the Carling Nations cup as recently as 2011, at his pre-match press conference ahead of Friday's Euro 2016 qualifier against Gibraltar, manager Martin O'Neill was unconcerned.
O'Neill said: "You were beating them in what competition? Mmm, it must have been a humdinger. It wasn't qualification for a European Championship or a World Cup, was it?
"I have won, honestly, in my time a couple of friendly matches myself, and I assume that they were strong friendly matches? I don't think you can make that judgement.
"What is a bit staggering is that Wales, having had not the best competition in the World Cup and having done very well in this competition, find themselves in front of England. I really don't know how that has come about, so that might tell you something.
"In terms of us trying to win some matches in major competitions, that's something that we have to look at. We didn't qualify for the World Cup, but we qualified for the last European Championships. We haven't historically qualified for that many since the competition started in 1960 and we will try to address that."