Oxford have signed midfielder Liam Davis on a one-year contract.
The 24-year-old, who can play on the left wing or at left-back, was released by League Two rivals Northampton at the end of last season.
Davis has impressed United boss Chris Wilder during a trial.
He becomes the ninth new arrival at the club this summer.
Davis started his career at Coventry, making 12 appearances.
He also had an eight-game loan spell at Peterborough before joining the Cobblers in 2008.
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