Newcastle striker Papiss Cisse could miss the entire holiday programme after an initial scan on his damaged groin proved inconclusive.
The Senegal international limped limped off 33 minutes into Saturday's 1-1 Premier League draw with Aston Villa at St James' Park after landing awkwardly, and is not only a major doubt for the St Stephen's Day clash but for the games which immediately follow.
Head coach Steve McClaren said: "He's had a scan and he needs a second opinion on another to gauge the severity, how long (he will be out). We still don't know, but he's a doubt for the weekend."
That represents a blow to McClaren, who has preferred Cisse to summer signing Aleksandar Mitrovic for the last four games, although the Serbia international came off the bench at Tottenham on December 13 to cancel out Eric Dier's opener and then set-up fellow substitute Ayoze Perez to clinch victory.
However, he has received better news on the injury front with a quartet of players - defenders Jamaal Lascelles and Steven Taylor, who both have hamstring problems, midfielder Rolando Aarons and striker Emmanuel Riviere, who are recovering from foot and knee injuries respectively - either back in training or ready to resume within days.
McClaren said: "Jamaal trained this morning for the first time; Rolando will train at the end of the week and Manu will be training by the end of the week.
"Steven Taylor is coming on really well, so a fortnight into January he could be back training as well, so it's good news on that front."
The Magpies play at 5.30pm on St Stephen's Day and will be in training on Christmas Day as they put the final touches to their preparations. McClaren said: "We'll train as normal. We'll be in nice and early and prepare for Everton. We have to be professional when others are enjoying it a little bit more and just make sure we focus and keep our intensity.
"The players will be in during the morning and then home. It will be normal preparation - with lots of present opening on Christmas Day."
Head coach Steve McClaren has voiced his support for former Newcastle keeper Pavel Srnicek (47) as he fights for his life after suffering a cardiac arrest. He said: "It's sad news, sad news. What a character - I remember him and he is really, really well-liked and loved by the Newcastle fans."