Former Celtic and Manchester United midfielder Liam Miller is having chemotherapy treatment for cancer.
The Irishman, 36, is reportedly on his way back to Ireland from the United States.
Miller, who won 21 caps for Republic of Ireland between 2004 and 2009, started his career at Celtic before moving to Old Trafford.
He also played for Leeds United, Sunderland, QPR and Hibernian before heading to Australia.
Miller played for three clubs down under – Perth Glory, Brisbane Roar and Melbourne City – before returning to his native Cork City.
He also played for semi-professional American team Wilmington Hammerheads in North Carolina last year.
News of Miller’s condition has been met with messages of support.
Republic of Ireland international David Meyler said the squad are thinking about their compatriot ahead of their play-off match against Denmark.
“Obviously we heard the news,” the Hull City midfielder said on Monday. “We’re unsure about the details, but our thoughts go out to his family and we’re just thinking about him and we just hope he can pull through and he’s strong. That’s from the whole team and everyone.”
Celtic wrote on their official Twitter account: “The thoughts and prayers of everyone at Celtic Football Club are with Liam Miller and his family at this time.”
And Manchester United tweeted: “The thoughts of everyone at Manchester United go out to Liam Miller and his loved ones at this difficult time.”
Former Celtic striker John Hartson, who recovered from cancer, tweeted: “My thoughts are with Liam Miller and his family this morning. Hope he can get through this difficult time of his life.”
Another ex-Celtic team-mate, Chris Sutton, tweeted: “All thoughts and prayers go out to my old teammate Liam Miller tonight.”