Barry Fry admitted his side were struggling after the loss of top scorer Leon McKenzie to Norwich, commenting: "One player doesn't make a team but it makes a hell of a difference." He added: " I am in for a busy week getting new recruits because that is what we need. The way we were today we could play for three days and not score." Wrexham manager Denis Smith enjoyed a double celebration - the three points and the presentation of a special award from the Football League marking his 1000th match as a manager.
The first half was dour and the home fans booed their players off at the interval, only to cheer them at the end after goals from Brian Carey and Hector Sam sealed the win.
Smith said: "I was pleased with the three points, but what happened in the first half was no substitute for football.
"The second half was a lot better and we deserved the win in the end." Peterborough came close to breaking through early on when Richard Logan rounded Carey, but stumbled as he tried to shoot and hit the ball at the goalkeeper Andy Dibble.
Posh were in with another good chance when Adam Newton crossed from the right and Carlos Edwards hacked the ball away with Dibble beaten and David Farrell waiting to tap in at the back post.
Steve Thomson hammered a 25-yard drive straight at the goalkeeper who saved easily and followed by holding onto a Logan cross as Andy Clarke raced in.
Gareth Jelleyman nearly found the target with a hopeful curling shot from 25 yards, which the keeper took under the bar.
Wrexham wasted early chances in the second half when Paul Edwards shot high over the bar from close range and Chris Llewellyn headed over when well placed to meet a Steve Thomas free-kick.
Carey broke the deadlock with a header from Jim Whitley's free-kick and substitute Sam sealed it with a delightful chip over keeper Mark Tyler, who was left stranded off his line as the ball bounced behind him and rolled into the net.