Sarkies has deep vein thrombosis (a blood clot) in his left arm and will miss the rest of the season with the Olyroo unable to take part in any contact training during his treatment.

The former Melbourne Victory midfielder, who scored his first Adelaide United goal in the loss to Sydney last Friday night, has been in hospital since Saturday morning and while he is expected to be released sometime this week. He will be sidelined for up to three months.

"We had a drinks break 20 minutes into the game (against Sydney FC), that's when I told the doc that my arm was about to explode," Sarkies said.

"I felt it about a week and a half ago when I slept with my arm above my head and woke up with a sore neck and sore shoulder. I pretty much thought nothing of it."

Giraldi was a late withdrawal from the team that faced Sydney FC after he was admitted to hospital for heart palpitations.

“I had a result back from the cardiologist and everything is fine,” Giraldi said.

“What they’re leaning towards is an anxiety attack. I feel OK now but the last few days I was feeling terrible.”

Giraldi will miss the trip to Newcastle to take on the Jets but may be a chance to return for United’s Round 20 match against Perth Glory on January 13.

Adding to Sarkies and Giraldi’s absence for this weekend’s game are the one match suspensions to defenders Robert Cornthwaite and Cassio, the former receiving a straight red card and the latter his fourth caution of the season against Sydney FC last Friday.

These additions to United’s unavailable list will severely test the squad’s depth this Friday night against the Newcastle Jets in a match The Reds must win to get back into the top four.