John Askey's first game as manager of Port Vale ended in a 1-0 defeat at Cambridge.
The only goal from David Amoo's defelected strike on 19 minutes.
The new Vale boss recalled striker Tom Pope back to his starting line up after he recovered from a hamstring injury.
The Valiants are now 20th in the table, five points above the relegation zone.
They are next in action on Saturday when John Askey's takes charge of his first home game against Morecambe.