Ten-man U's sunk by HattersMARK Cullen scored the winner as Luton claimed all three points this afternoon.
Cullen's penalty was saved by Dunn, but the Hatters striker was first to the ball and hammered home.
United started the game brightly, with Ryan Donaldson firing just wide on 18 minutes and Tom Elliott striking the post on 25.
Alex Wall had the visitors best chance of the first half, his free-kick ending up wide of Chris Dunn's right hand post.
HT: U's 0-0 Luton
A lively second half saw the U's reduced to ten men in the 54th minute. Tom Naylor shown a straight red for a high tackle on Jim Stevenson.
Pelly Ruddock rattled the crossbar for the visitors in the 66th minute, before Luke Wilkinson headed over Chris Dunn's bar.
The deadlock was broken on 81 minutes, with Cullen converting from close range.
Greg Taylor came closest for United in the final stages, his shot finishing up wide of Mark Tyler's right hand post.
FT: U's 0-1 Luton
TEAM: Dunn, Tait, Coulson, Nelson, Taylor, Naylor, Donaldson, Dunk (Diallo, 73), Simpson (Hurst, 77), Elliott, Appiah.
NOT USED: Norris, Lanzoni, Lennon, B Taylor, Bird.
ATT: 6533 (2050 Away)