But Chris Hughton (who may not be a good manager - but is incredibly loyal to his players) has shed some light on the matter.
The unsettled defender – who has gone public with his intention to quit St James's Park this summer – is the only player not to have featured in any of the club's four pre-season friendlies.
Hughton: "Sebastien's now back training with the group.
"What he has done is a different programme.
"Hopefully, he can play some part on Wednesday. He played a little bit later than everybody else (with Cameroon). He had a little problem towards the end of last season.
"It hasn't been an issue. We've just needed to make sure we managed it."