Aleksandar Mitrovic has not linked up with the rest of the squad in La Manga.
Newcastle United manager Steve McClaren has told the club's official website that Aleksandar Mitrovic's absence from the squad's training camp at La Manga is because the striker has suffered a knee injury.
With the Magpies not playing again competitively until the end of the month, McClaren announced a 26-man squad for the trip, a list from which Mitrovic's name was conspicuously missing along with Papiss Cisse's.
While Cisse is recovering at the club's training ground following a recent injury, Mitrovic was left out because of a new problem, although his manager remained confident that it would only a short-term issue.
McClaren told the club's website: "[Mitrovic] has got a knee injury. We're only bringing players here who can actually train over the next four days, and play in the game on Saturday.
"Mitro has a medial ligament injury, so it could be a couple of weeks - we're hoping not too long."
The news will come as a blow to Newcastle fans and will be hoping that the man who has added five goals in 22 Premier League appearances to the Magpies survival bid is able to recover quickly.
The 21-year-old Serbian international moved to St. James' Park last summer after netting 36 goals in 69 Belgian league games during a two-year spell with Anderlecht.
Newcastle are currently third-bottom of the Premier League table, in the relegation zone on goal difference.