Mbemba and Sels have both left Newcastle this summer.
Sels, 26, finally ended his nightmare two-year spell on Newcastle's books after first joining the club in the summer of 2016. He made 14 appearances for The Toon but a string of mistakes in 2016-17 saw him ostracised.
The Belgian was loaned to Anderlecht for the entire 2017-18 campaign and has now left Newcastle on a permanent basis, with Strasbourg opting to chance their arm on the goalkeeper.
Mbemba, who also left Newcastle this summer to join Portuguese giants FC Porto, sent a message to Sels on Instagram, wishing his former teammate all the best in France's top tier.
His message is translated as: "I am proud of you my brother, good luck over there."
Sels was considered surplus to requirements with Newcastle opting to make Martin Dubravka's loan a permanent one, for the same fee in which Sels was sold. Newcastle also boast Rob Elliot, Karl Darlow and Freddie Woodman as options.
Mbemba also found himself on the transfer list, and made the somewhat surprising move to Champions League outfit Porto. His departure has since seen the club land Fabian Schar for a bargain fee of £3million from Deportivo.
Have something to tell us about this article?