Cristian Montano will remain on loan with Oxford United until the end of the season after an extension was agreed with parent club West Ham.
The 20-year-old joined last month and has two goals in seven appearances for the U's.
The extension will include the npower League Two play-offs, if United finish the campaign in the top seven.
Montano said: "It's good to have everything sorted, I have enjoyed my time here and it is a good club.
"There is a lot of ambition here and everyone wants to get into League One and I am happy to try and play my part in that aim.
"Hopefully I can help the team achieve that with one last extra push."
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