Steven Gerrard revealed new signing Nnamdi Ofoborh's Rangers career will be put on hold after scans revealed a heart issue.
The 21-year-old midfielder moved to Ibrox on a free transfer from Bournemouth this summer but a medical "red flag" emerged.
After watching Rangers draw 2-2 with Arsenal in their friendly at Ibrox, Light Blues boss Gerrard told RangersTV: "I don't think you'll see him in the short term.
"Unfortunately something has flagged up with his ECG, which is the heart test.
"We've got top medical people here at the club now and we check all the players thoroughly from head to toe when they arrive.
"Unfortunately there's been a bit of a red flag with a heart issue so he's going to see some specialists in the coming weeks and we need to do more tests before we move forward.
"It's disappointing and frustrating but we'll have to manage and cope.
"The important thing is the player's health, which we'll obviously focus on first and foremost.
"Of course it is disappointing and frustrating for the player but I spoke to him yesterday, told him to keep smiling and be patient and we will do everything we can to support him, get him in front of the right people and the right support and hopefully he will be back, not too long."
The news comes just over a month after Denmark midfielder Christian Eriksen suffered a cardiac arrest and collapsed on the pitch during his country's Euro 2020 opener against Finland.
Gerrard was more positive about the hamstring injury to veteran striker Jermain Defoe.
With a new Premiership campaign and a Champions League qualifier looming, the 38-year-old limped off before half-time after a Leon Balogun header for Rangers had been cancelled out by Nuno Tavares, the Portuguese left-back who was making his Arsenal debut after signing from Benfica.
Gers striker Cedric Itten headed in a corner from fellow substitute Glenn Middleton in the 75th minute after both sides made numerous changes but that was cancelled out in the 83rd minute by a drive from Arsenal replacement Eddie Nketiah.
Former Liverpool and England captain Gerrard said: "I think (Defoe) has a little tweak in his hamstring so we will check that out in the coming days and hopefully it is not a bad one.
"I saw him walk off and normally when it is a bad hamstring you don't walk off and so that is a positive.
"We just need to get all our main players back in the mix now and get them up to speed and once we do we will be fine."
