Antonio Valencia slid in on Anita, leaving the Newcastle man needing to be stretchered off with an injured ankle.
"I was a bit upset with that tackle," said Pardew. "I have seen it again and I don't think it was malicious but Valencia has mistimed it badly and unfortunately it might cost us a player.
"I am not sure what is wrong. It is too early to say.
"It is a bang on the ankle. We will have to see whether he will make Arsenal, which would be a loss to us."
Three times Newcastle led, through James Perch, a Jonny Evans own-goal and Papiss Cisse, only for Evans - becoming the third player this season to score at both ends - Patrice Evra and Robin van Persie, with his 16th goal of the season, to respond.
Further chances came and went in a thrill-a-minute game but when Sammy Ameobi struck the inside of a post with a shot Pardew thought was going in, he feared the worst.
"When it went back to the goalkeeper I thought `mmm, it might not be our day'," said Pardew.
He was right. And it wasn't Manchester City's either as Javier Hernandez struck in the dying seconds to ensure United will be top on New Years' Day.