The 24-year-old spent last season on loan at Sao Paulo, but had been linked with a return to Arsenal.
He told Gazeta Esportiva: “I don’t know what happened. I just expressed an interest in staying at Sao Paulo for at least another year. The chiefs on Arsenal’s board helped.
“I didn’t talk to Arsene Wenger. My lawyer and I met Sao Paulo’s board and we agreed it would be better if I stayed at the club, and they reached an agreement with Arsenal.
“Thank god everything worked out. I’ve been training well and I’m ready for Sunday’s game.”
