Already without skipper Gary Ablett (knee) and defender Jarrod Harbrow (elbow), Rischitelli arrived at Suns training on crutches on Friday after injuring his ankle at training this week.
Coach Guy McKenna said Rischitelli could miss multiple weeks.
"When he walked in today on crutches, it probably said he wasn't going to be able to get up," McKenna said on Friday.
"He could potentially miss two to three weeks actually."
Midfielder David Swallow, who is battling hip soreness, remains on track to play.
