The midfielder limped off with a slight muscle strain in last Saturday's 0-0 draw with Blackburn, the fourth successive game in which Boro have failed to score, but Karanka is hoping he will be fit for the Sky Bet Championship trip to Vicarage Road.
Karanka told the Northern Echo: "It would be a big blow not to have him because over the past few weeks, he has played very well.
"I think he is now a stronger player. He was already a good player, but now he can fight for 90 minutes and that makes him an amazing player.
"To be that, he needed to be stronger than he was and for this. I am happy.
"He needs to keep working in the same way because all the players are working very well and to be in the first 11 is not easy. It is hard to get a place when the team has improved."
- Sports & Recreation
- muscle strain