The pair are set to go head-to-head when Manchester United take on Saint-Etienne in the last 32 of the Europa League at Old Trafford on Thursday
The pair will be on opposite sides when Manchester United entertain Saint-Etienne in the first leg of their Europa League last-32 tie on Thursday.
Florentin, who has his sibling's shirt number six shaved and bleached on the right side of his head and his own, 19, on the left, is looking forward to the renewal of their rivalry.
"I beat him at table tennis. After that we did not play other sports together," said the left-back at a pre-match news conference.
"[We have joked together] right from the draw, but since then we have remained focused on what we should do with our teams.
"After tomorrow evening [Thursday], we will swap shirts and it will be a wonderful moment, magical.
"There is only excitement, not anxiety. In a legendary stadium and against my little brother, there is nothing more beautiful for me."
"Of course, it will not be easy for her. My mother will be present at both matches," he said.
"She does not want a loser in this match, but there will be one – except for my mother, she will have no victor."