The Brazilian has regularly attracted the ire of Gunners fans during his time at the club, and never more so than when he asked for former team-mate Robin van Persie's shirt at half-time as the north London side slipped to defeat against Manchester United earlier this season.
But, after the 29-year-old replaced the injured Kieran Gibbs during Arsenal's thrilling 2-2 draw with Liverpool on Wednesday, Santos has promised his performances will improve.
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First-choice left-back Gibbs' injury is set to keep him out for three weeks, and Arsene Wenger has admitted he may need to sign a replacement.
"Gibbs has a thigh strain and that rules him out for the next three weeks – it is a big blow for us,” Wenger told reporters.
"I’ll see what I can do. Gibbs was a big player for us going forward and in the game we want to play.
"I cannot promise you any transfers. We work on it. We want an official extension of the window for one week."