Cambridge United are leading Luton Town at half time of their FA Cup third-round clash.
Luton were the first side to create a real chance, and they almost took the lead after eight minutes when stand-in captain Jonathan Smith cannoned the post from 20 yards.
The home side had the majority of possession early on and they made it count when Luton keeper Mark Tyler brought down Ryan Donaldson in the box, forcing the referee to award a penalty.
Tyler managed to save Robbie Simpson's effort, but the striker hammered in the rebound to give the home side the lead.
The Hatters pressed for an equaliser immediately and almost found one when a corner was headed across goal for Jim Stevenson, but he put the ball over the bar from the edge of the box.
