Oxford wrecked Jimmy Dack's Newport send-off with a 1-0 win at Rodney Parade.
Kemar Roofe smashed Michael Appleton's men into a first-half lead before County stalwart Michael Flynn saw red.
Dack could only guide the Exiles to a ninth-place finish and hands over managerial duties to former England captain Terry Butcher.
The three-points meant Oxford ended the season in 13th position.
Roofe fired the Us in-front in the 31st minute. Former Newport man Danny Rose slipped a through ball to the striker who...