Shaun Derry enjoyed a triumphant return to 10-man Notts County as his Cambridge United team maintained their Sky Bet League Two play-off assault with a 2-1 win at Meadow Lane.Having been sacked by the Magpies last March, Derry still received a warm welcome from the home fans and acknowledged them with a thumbs up.But he was punching the air in delight after four minutes when Luke Berry charged down a clearance from Scott Loach which flew into the far corner.Harrison Dunk's volley crashed off the foot of the post as Derry's men went close again.It proved a decisive moment as Notts were back on level terms before half-time when Haydn Hollis met a Liam Noble free-kick which Will Norris could not keep out.Notts sensed they could go on and win the game in the second half, but it was Cambridge who made the vital breakthrough.After a corner was poorly defended, the ensuing goalmouth scramble was eventually ended when Ben Williamson tapped in at the back post.Notts' misery got worse as Noble was sent off for a poor challenge on Darnell Furlong with nine minutes remaining while Cambridge remain five points adrift of the play-offs.