Martin O'Neill is set to battle it out with his former club for the signing of Croatian hotshot Mario Mandzukic.
The 23 year old striker was the top scorer in the Croatian league last season scoring 16 goals in 28 appearances for Dinamo Zagreb.
Mandzukic is currently valued at around £8m and the man who replaced Eduardo at the club after the Brazilian signed for Arsenal is sure to be popular during the transfer window.
However, Celtic are unlikely to be able to meet Dinamo's price tag, meaning the door is wide open for O'Neill to swoop.
Stoke City and Steve Bruce's Sunderland are also thought to be monitoring the situation.