The former Brentford striker joined the Magpies in a £55 million deal on Deadline Day but manager Eddie Howe has revealed his new signing is "feeling the effects" after suffering a knock when he turned out for DR Congo against Senegal during the recent international break.
He said: "An established Premier League goalscorer is difficult to find. He's got outstanding qualities, a history of scoring goals, and always did well playing against us [in the past].
"I admire the journey he's been on, he's made big steps in his career and adjusted and made them. Hopefully he can do that for us.
"He won't make this game. He's feeling the effects of the injury he picked up while he was away."
And Eddie is unsure how long it will be before his new signing is back to full fitness.
Asked to comment on how long Wissa might be missing, he added: "It's a knee injury but I don't know any more. He'll go away for tests and see a specialist. I can't give you an update."
The manager praised his other new signing, Nick Woltemade.
He said: "He's fine. He's trained well. I've been really pleased. A big change for him and a big opportunity.
"He's got a great nature, he's very calm, showed his qualities. Really pleased with how he's settled. He's laid back, relaxed and funny, very warm person. He wants to help the team, very selfless in that respect."
