Cambridge conjured up a win over 10-man Tamworth to end a run of four straight Blue Square Bet Premier defeats.
Charlie Wassmer's delivery was headed home by Tom Elliott - his 14th goal of the season - to give the U's the lead.
Michael Gash then doubled the advantage after the break from the penalty spot after Richard Tait fouled Elliott.
And despite seeing team-mate Lee Hendrie dismissed for a push on Tom Shaw, Adam Cunnington struck a powerful free-kick for a late Lambs consolation.
Cunnington's strike was his 17th goal of a fruitful season, but was not enough to help Tamworth go three unbeaten.