Stunning first-half strikes from Daniel Fox and Chris Westwood ensured Walsall took another step towards promotion with victory at Peterborough.
Fox broke the deadlock with a fierce 14th-minute volley from 30 yards.
He then delivered the cross for Westwood to double the advantage with a magnificent finish nine minutes later.
Martin Butler was denied a third Walsall goal by a last-ditch Mark Arber tackle, while Danny Crow and Adam Smith came close at the other end.
Peterborough: Rachubka, Futcher, Morgan, Arber (Benjamin 46), Newton, Huke (Stirling 82), Butcher, Strachan (Yeo 69), Smith, Mclean, Crow.
Subs Not Used: Branston, Opara.
Walsall: Ince, Pead, Westwood, Roper, Fox, Mark Wright, Dobson, Taylor, Dann, Butler, Sam (Bedeau 63).
Subs Not Used: Bossu, Keates, Demontagnac, Bradley.
Booked: Fox, Sam.
Goals: Fox 14, Westwood 23.
Ref: D McDermidd (Catterick).