A scrappy game between Cambridge and Mansfield ended goalless at the Abbey Stadium.Neither goalkeeper was tested in a first half short of incident, though the home side looked the brighter, with debutant Billy Waters impressing up front.The Northampton loanee was inches away from connecting with an Adam Phillips free-kick and was involved in the move that led to left-back Jake Carroll firing over when well placed.Mansfield goalkeeper Conrad Logan made a good save shortly after the restart to foil Uche Ikpeazu from close range with his legs, but it was the Stags who looked the more likely to break the deadlock thereafter.Danny Rose volleyed over from CJ Hamilton's cross and Alex MacDonald went close with a free-kick that had to be palmed over the crossbar by U's keeper David Forde.Rose also had the ball in the net after a spell of penalty-box pinball, but his celebrations were cut short by the offside flag.