Linfield have sent their best wishes to Paul Smyth after the former Blues forward suffered a collapsed lung playing for Leyton Orient.
The 24-year-old Northern Ireland spent the night in hospital after having to be substituted late in the first half against Mansfield.
O's boss Kenny Jacket said afterwards: "It's not good news.
"It was a challenge on about 40 minutes of the first half and he has a collapsed lung. He was in hospital on Saturday night.
"He is in good spirits and is being looked after well but in terms of his football he won't be with us for a little while."
Smyth left Linfield in the 2017 to sign for QPR in the Championship, and has also had spells with clubs including Accrington Stanley, Wycombe and Charlton.
The Blues said on their social media: "The best wishes of everyone at Linfield FC are extended to popular former player Paul Smyth who suffered a collapsed lung in last weekend's League Two defeat for Leyton Orient at Mansfield.
"Everyone at Linfield wishes Paul a full and speedy recovery. Audaces Fortuna Juvat."
Manwhile, Smyth - who has scored one goal in 12 appearances for Orient - tweeted: "Life is 10% what happens to you and 90% how you respond to it.
"I will be back once again."
