The midfielder revealed on Twitter that he is set for a spell out ahead of the visit of Manchester United, joining Loic Remy, Tim Krul and Mathieu Debuchy on the sidelines
Sitting comfortably placed in ninth position in the table, Newcastle's season is in danger of petering out after back-to-back defeats at the hands of Everton and Southampton.
|9/2||Newcastle are 9/2 with bet365 to beat Man Utd by one goal|
"We've got a real injury crisis at the moment," Pardew told reporters.
"We've lost Moussa this week, so of the team that started when we beat Manchester United [away], five won't play, although one [Yohan Cabaye] has left the club.
"Moussa has a hamstring strain and we think it will be two or three weeks. He's been a terrific player for us, and has had a great season.
"[Loic Remy] was finding his feet a little bit last season, but this year has served him well.
"Will he be ready for the weekend game? No. We think he's got a chance for Stoke, but we thought he had a chance for this week and are a little bit disappointed that he hasn't."
Sissoko confirmed his absence on Twitter, and joins Loic Remy (ankle), Tim Krul (knee) and Mathieu Debuchy (groin) on the sidelines.
The midfielder did not reveal the nature of his injury, but confirmed that he will be absent for at least a fortnight, tweeting: "Early rehabilitation Clairefontaine today!! Back in 2 or 3 weeks!!"