The England striker was substituted at half-time during Villa’s midweek Champions League triumph over RB Leipzig and replaced by Jhon Duran, who scored seven minutes after the break.
Villa return to Premier League action on Saturday and Emery confirmed a decision about Watkins will be made after Friday’s training session.
“We trained yesterday but it was a recovery day and some players as well rested,” Emery said.
“Today we are going to try to train and to know how we are after four matches in a few days.
“Tomorrow is going to be as well a very difficult match and we have to try to play with the best players we have or with the best players who are, more or less, full in everything – energy, fitness, good rest.
“This afternoon is the key for how we can go tomorrow.”
When asked specifically about Watkins’ availability, Emery replied: “I don’t know because we are waiting.
“Yesterday he was recovering and this afternoon we are going to train. In case he is training normally and he is feeling good, he’s going to be available for tomorrow. If (he’s) not, not.”
Both Villa and Forest are locked on 25 points going into Saturday’s game and Nuno Espirito Santo’s side sit just above the Villans on goal difference.
An impressive campaign has seen Forest record seven wins in the league so far, including a brilliant victory over Manchester United last weekend to record their first win at Old Trafford since 1994 and Emery believes the club have had an “amazing season”.
“Forest of course are always a respected team for us,” Emery added.
“They’re now a rival because they are with the same points we have, they are doing an amazing job, an amazing season.
“Last season we played in different circumstances and lost there. I know how much difficulties we are going to face tomorrow. They have Nuno and he was their coach when we played here at Villa Park.
“But now I think I can see Nottingham Forest with his face and his identity. He’s always very competitive, Nuno. As a coach, I played against him in Spain and in my experiences before in the Premier League against Wolverhampton when I was in Arsenal.
“Always the matches we played were very difficult for us – we lost against Wolverhampton in that moment.
“His experience is very important, even in Europe. Wolverhampton in the Europa League because they finished seventh in the league and got to a quarter-final against Sevilla.
“I am telling that because I am watching something like that here with Nottingham. He’s got a very competitive team and he is now being a rival for the team. We are more or less trying to fight in the table to be in the top European position.
“Tomorrow they are our opponent, our rival and a very difficult team we’re going to face. I’m excited, motivated and I respect them a lot.”