Dwight Gayle is facing a spell on the sidelines after suffering a hamstring injury in Newcastle United's 2-1 win over Brentford.
And the striker – who has become the first player since Alan Shearer to score 20 goals for the club – will be assessed over the next few days by the club's medical staff.
Isaac Hayden suffered a groin injury in the game, while Vurnon Anita was stretchered off with an ankle problem.
United manager Benitez said: "We have the doctors telling me that we need to check them tomorrow to see how they are.
"To make substitutions is always not good news, but in the end we had to do it. I'm really pleased with the players coming off the bench. They performed well in a difficult game.
"I am sure that the fans will be very proud of the team today, because they were working so hard in a difficult situation."
Asked if Gayle's withdrawal was precautionary, Benitez added: "No. The the three of them we had to make a substitution.
"It was a bad tackle on Anita. He has a problem with his ankle. Hayden with his groin, and Gayle with his hamstring."
Lasse Vibe cancelled out Gayle's goal early in the second half, but substitute Daryl Murphy claimed all three points for United with his first league goal for the club.
The result saw United go a point clear at top of the Championship after Brighton and Hove Albion were beaten 2-0 by Preston North End.