The Welsh had fallen to 10th - equalling their lowest ever ranking - before ending an eight-match losing streak with a win over France a fortnight ago, but now sit just under half a rating point below France in fifth.
However, had Ireland not slipped to a 12-8 loss to Scotland at Murrayfield a day later then Wales would have remained seventh after the 26-9 win over Italy.
Ireland's second defeat of the Championship now leaves them just over half a rating point above Samoa and Argentina below them, while back-to-back wins for Scotland mean they are within a point of the Irish now.
Scotland remain 10th and now have Tonga beneath them after Italy fell one place to 12th on the back of the Welsh defeat. The Azzurri, however, are still more than three rating points above Fiji below them.
England have also strengthened their position as the leading northern Hemisphere nation in the rankings following the 23-13 win over France at Twickenham.
Stuart Lancaster's men now sit just over four points above France and are gradually closing the deficit to Australia above.
IRB WORLD RANKINGS (as of Monday, February 25):
Last week's positions in brackets -
1(1) New Zealand 90.08 rating points
2(2) South Africa 86.94
3(3) Australia 86.87
4(4) England 85.30
5(5) France 81.20
6(7) Wales 80.74
7(6) IRELAND 79.28
8(8) Samoa 78.71
9(9) Argentina 78.71
10(10) Scotland 78.19
11(12) Tonga 76.10
12(11) Italy 74.93