The forward appeared to suffer a back injury during their most recent Premier League game.
Welbeck had scored what turned out to be the winner against Newcastle before having to go off.
This week, Hurzeler told reporters: “It's too early to say if he can play or not, but he will train today and then we then we will see afterwards how this training session goes and then we will make a decision.”
On the nature of the injury, he added: “He got hit on a nerve and then when you get a hit on the nerve, then you don't feel the leg for an amount of time and that’s exactly what happened.
“It's very painful and it's still painful. But again, we have to make a check today in the training session and then he has to have a lot of treatment.
“Our medical staff and our physios, they're working every hour with him together to make him fit for the game. This will be the challenge for us, but hopefully everything will be good.”