Interim boss Guus Hiddink revealed yesterday the striker suffered the injury in a training ground collision with academy player Canadian defender Fikayo Tomori, who was training with the first-team squad.
“Diego got in a duel, got his nose broken,” Hiddink said. “He put his nose on the back of the head and he was very unlucky.”
Costa is poised to join full-back Cesar Azpilicueta in wearing a protective face mask in today’s Premier League clash with the Magpies. Azpilicueta is recovering from a fractured cheekbone.
The striker’s mask was due to be fitted yesterday.
Hiddink said: “Today is the day they put on a mask. We are a team with a lot of masks. A Zorro team.”
Nemanja Matic and Gary Cahill have also worn protective masks this season, while Cesc Fabregas is among those to have worn masks in recent seasons.
Costa has scored seven times in nine games for Chelsea, including to earn a 1-1 Premier League draw at home to Manchester United last Sunday.
That was a reminder of Chelsea’s reliance on Costa, with Loic Remy (calf) out in recent weeks and Radamel Falcao out since October.
Chelsea’s defensive options have been reduced, too, after Kurt Zouma suffered a season-ending knee injury against United, meaning a likely return to the Blues’ starting XI for Cahill against Newcastle.
Hiddink would not be drawn on whether the blow for Zouma might have implications for captain John Terry.
The 35-year-old last month announced Chelsea would not be renewing his contract, but the club insisted the possibility remained that the captain would be offered an extension.
Hiddink said: “That’s something to be answered by the management and the board and the directors of the club.
“The door was open and is open. We’ll see what will happen with this.”