Republic of Ireland manager Giovanni Trapattoni has handed over the reins for Wednesday night's friendly against Argentina to assistant Marco Tardelli.
The Football Association of Ireland have confirmed Trapattoni will undergo further tests at Dublin's Mater Hospital after the 71-year-old was admitted on Tuesday with suspected food poisoning.
An FAI statement read: "Republic of Ireland manager Giovanni Trapattoni's condition remains stable in the Mater Hospital. His progress overnight has been slightly behind expectations, and after being seen by his consultant he will undergo further investigations. Assistant manager Marco Tardelli will take charge of the Republic of Ireland squad for the match against Argentina."
Trapattoni was taken to hospital at 3am on Tuesday morning, with the FAI citing the cause of his illness as shellfish eaten prior to him leaving Italy on Sunday.
Tardelli and captain Robbie Keane had both expressed hope the 71-year-old would be fit to take his place in the dugout.
But ahead of Ireland's first game at their new £350million home, the 50,000-seater Aviva Stadium, it is Tardelli who has the honour of managing the team as they embark on a new era.