Wales have dropped down to eighth in the world rankings despite recently reaching the semi-final of the Rugby World Cup in New Zealand.
Warren Gatland's side were within two points of progressing to the final, eventually losing out to France 9-8 two weeks ago.
They are the only side to fall down the International Rugby Board's latest list, having started the tournament in sixth.
World Champions New Zealand remain top, trailed by Australia and runners-up France.
South Africa and England make up the top five, while Ireland move up to sixth.
