Arsenal has agreed to a deal with Villarreal involving Gabriel Paulista and Joel Campbell.
Gabriel, a 24-year-old central defender from Brazil, will go to Arsenal for £13.5 million.
Campbell will go to Villareal on loan from the Gunners for the remainder of the season.
Campbell was expected to have a breakthrough campaign for Arsenal this season. He had an excellent loan spell at Olympiacos and a very strong World Cup, but has made only 10 appearances this year and has not scored a goal.