He is facing four months on the sidelines after he suffered a thigh tear in training.
Former Ajax skipper
Many were surprised when the transfer went through in the summer because De Jong does have pervious - he had a long spell out last season at Ajax with a collapsed lung!
I'm sure the 25-year-old is a major part of Pardew's future plans, even though it has been suggested the Toon boss had nothing to do with the transfer, and it was Newcastle scouts who set up the deal.
That can be very worrying, and smacks of the problems that was caused in Kevin Keegan's second spell as boss when Dennis Wise drummed up all of the deals ... and KK hadn't heard of some of the players that arrived.
Big boots to fill
But Mike Ashley's plan is for "others" to do the deals, and Pardew to mould them into a force.
Pardew calls him the "new Cabaye", but what we've seen of Siem de Jong ... he has a hell of a lot to live up to.
Perhaps he really IS as good. We will see.
Alan Pardew: “We have got fingers crossed that he comes back in January ready to go, because the injury he’s got is such that we have to be very careful with his rehab and make sure that we don’t put him at risk.
“His thigh muscle had a tear at the top where it joins the bone, and that’s a dangerous area.
“We are missing him because he was obviously a massive signing for us.
“He was captain of Ajax, a fantastic pedigree.
“He’s yet to do it in the Premier League, of course, but we had good confidence that he could.
“He’s the link that I think we have missed, well since Cabaye went, really, so it was a blow.
“But we have to ride those blows out and we have to be good enough to cope with it, and that’s really where we are now."