Jackson Irvine
Midfielder Irvine has enjoyed a prolific season with Championship side Burton Albion this season, scoring 10 goals in 36 games as the Brewers narrowly avoided relegation in 20th place.
Australian outlet The World Game claim that five second-tier sides are interested in Irvine, who made one Celtic appearance after moving to Glasgow from his home country as a 17-year-old in 2010.
Celtic should keep a close eye on the midfielder who is expected to feature in midfield, and potentially look to rival Aston Villa, Derby, Wolves, Fulham and Sheffield Wednesday for his signature.