A goal in each half brought Oxford a 2-0 win over Tranmere in the battle of the bottom two clubs in Sky Bet League Two.Tyrone Barnett struck in the 28th minute and substitute Alfie Potter sealed the points with a smart shot in the second half. New boss Micky Adams was watching Tranmere for the first time since his appointment, before officially taking charge of the team next week.Young left back Tareiq Holmes-Dennis, making his debut on loan from Charlton, was instrumental in Oxford's opening goal. The teenager spread play with a long diagonal pass, and from Danny Hylton's low right-wing cross, Barnett swept home.Ryan Clarke saved from Max Power early on, but Rovers posed little threat after that.Barnett, in contrast, was a real menace, and he might have had a hat-trick before half time, Slovakian keeper Peter Brezovan denying him with two terrific saves.Hylton shot against the underside of the bar from close range, from O'Dowda's pass, in the second half.Then Potter drove home at the far post with 17 minutes left after Hylton had missed Joe Riley's inviting cross.