The Dutchman injured his knee against Everton and will miss Saturday's test against Mauricio Pochettino's Saints, who are one point behind the eighth-placed Magpies
The Netherlands goalkeeper suffered the setback in Tuesday's 3-0 home defeat at the hands of Everton and will not make the trip to the south coast this weekend.
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"Tim won't play," he confirmed to reporters on Thursday. "He's out for the next two or three games for sure, so Rob Elliot will come in.
"[Elliot] has made his international squad and he's keen to stay in that squad. He needs to play, so the opportunity has landed at his feet.
"Rob's a confident goalie and he'll look to take that on."
Pardew also had updates on a number of Newcastle's other injury concerns.
"Davide Santon is back in training, and that's good news for us," he said. "That's probably our full complement.
"We think [Loic] Remy will train on Monday, which means that he's going to train over the weekend, so he's got a good chance for Manchester United.
"Mathieu [Debuchy], we think will be a bit longer than that - maybe another couple of weeks."