Dan Ballard has been ruled out of Northern Ireland's World Cup qualifying play-off semi-final against Italy with a hamstring injury.
The news had been expected after Ballard sat out Sunderland's 2-1 win over rivals Newcastle on Sunday with the injury he suffered in last week's defeat at the hands of Brighton.
It is another significant blow for Michael O'Neill, who is already without Liverpool's Conor Bradley for Thursday's match in Bergamo, the winner of which will face either Wales or Bosnia-Herzegovina for a place at this summer's World Cup in the United States, Canada and Mexico.
O'Neill has replaced Ballard in his 28-man squad with 19-year-old defender Tom Atcheson, who the manager has been working with directly since taking the Blackburn job alongside his international duties last month.
It is a first senior call-up for Atcheson, who has played at several youth levels up to the Under-21s for Northern Ireland. This season he has made eight first-team appearances for Rovers, starting their goalless draw with Middlesbrough on Saturday.
O'Neill's squad met up in Liverpool on Sunday night and will spent the week training in the city before flying to Bergamo on Wednesday afternoon.
Italy, meanwhile, have lost Liverpool winger Federico Chiesa for the visit of Northern Ireland due to a fresh injury problem.
Chiesa played the last 13 minutes of the Reds’ 2-1 Premier League defeat at Brighton on Saturday but has also been ruled out of Italy's potential play-off final, possibly against Wales, on 31 March.
"Federico Chiesa, whose condition was assessed upon arrival at the Federal Technical Centre, was deemed unavailable for the next two matches and, in agreement with the club, left the national team's training camp," the Italian Football Federation said.
Bologna forward Nicolo Cambiaghi has been called up by Italy boss Gennaro Gattuso to replace Chiesa.
