Oxford have moved quickly to replace Marvin Johnson with the signing of Alex Mowatt from Barnsley.
The 22-year-old has dropped down a division to join Sky Bet League One Oxford on a season-long loan.
Former Leeds player Mowatt previously worked with Oxford boss Pep Clotet at Elland Road and arrives at the Kassam Stadium just hours after Johnson was sold to Middlesbrough.
Clotet told the club's official website: "We were interested as soon as we found out there was a possibility of getting him because we feel he is a player who adds to our creative options.
"He can play in any position in the midfield and although he is still only 22 he has played well over 100 games in the Championship and has lots of experience for his age.
"He is the right type of player for us, one who wants to work hard and be part of what we are building. I am sure he will do very well for this club."