Andy Clarke's ninth goal of the season was enough to hand Peterborough a win over Chesterfield that eases some of the pressure on manager Barry Fry.

Fry's shrewd 80th-minute introduction of lanky frontman Jason Lee turned a tight game in Posh's favour.

The former Chesterfield striker nodded a Matthew Gill centre into the path of veteran Clarke who found space to fire home from close range.

A succession of crosses by Peterborough's Helgi Danielsson was the high spot of a poor first half that saw the home side fail to outwit a well-organised Chesterfield defence.

Impressive home midfielder Jimmy Bullard brought a superb one-handed save from Chesterfield goalkeeper Carl Muggleton.

Danielsson also had a 20-yard effort which beat Muggleton but smacked against a post.

Peterborough: Tyler, Gill, Rea, Edwards, Burton, Jelleyman, Shields, Bullard, Danielsson, Andy Clarke, Allen. Subs: Pearce, Farrell, Lee, Newton, Fenn.

Chesterfield: Muggleton, Davies, Dawson, Payne, Howson, Rushbury, Booty, Hudson, Brandon, Burt, Reeves. Subs: Rowland, Richmond, Howard, Allott, O'Hare.

Referee: L Mason (Lancashire)