Celtic Front Office
Moussa Dembele has been a revelation for Celtic this season, scoring 16 goals in 26 games in all competitions.
Neil Lennon and David Moyes were also candidates but Celtic has decided upon Brendan Rodgers.
Southampton are close to a £10 million deal with Celtic for goalkeeper Fraser Forster.
Legia won the third qualifying-round tie 6-1 on aggregate but brought on Bartosz Bereszynski for the last four minutes of their 2-0 second-leg victory at Murrayfield.
Neil Lennon had grown disillusioned with the lack of challenge offered by Scottish football.