Thorgan Hazard's move to
Hazard is expected to follow in the footsteps of his more celebrated elder brother Eden by joining the Blues and his Ligue 1 employer appears to have accepted the move is inevitable.
Sibierski told his club's official website: "It should be official tomorrow. (When I arrived) there was no intention of letting him go and I met him very quickly after my arrival to show my confidence in him.
"He still had one year left and it was proposed he extended it but he told me eye to eye that did not interest him and he wanted to leave Lens.
"I realised 48 hours later why, when I learned Chelsea wanted him. I understand."
He added: "He is a boy of 19, his elder brother signs for Chelsea and he is urged to do so by the same club, who won the Champions League.
"Congratulations to Thorgan. Unfortunately we cannot go against such an opportunity. Good luck to him."
English Premier League
West Ham United has completed its first transfer of the post-season after signing Romania international fullback Razvan Rat on a free transfer.