Cambridge warmed up for the visit of Manchester United in the FA Cup next weekend with a comprehensive 4-0 victory over Newport.Debutant Cameron McGeehan, signed on loan from Norwich this week, had already clipped the crossbar with an effort when he gave the U's a 12th-minute lead. He slotted the ball past goalkeeper Joe Day after Ryan Donaldson's cross was deflected into his path. Sulley Kaikai fired wastefully wide after bursting through but he made amends when doubling the lead two minutes before the break, receiving Tom Champion's pass and arrowing a low finish across Day from outside the box. Newport's best chances came through Ryan Jackson, who fired wide when unmarked, and Mark Byrne, who headed narrowly off target from Ryan Jackson's cross on the stroke of half-time. McGeehan made it 3-0 after 64 minutes, stroking home from close range after Donaldson led a quick break away move and crossed from the right. Liam Hughes completed the rout with 11 minutes left when he smashed home the rebound after his own header came back off a post.