Slimani, who joined the Magpies on loan from Leicester City until the end of the season on transfer deadline day, has been unable to fully train with his teammates this week as he continues to recover from a minor thigh problem.
That knock has prevented him from making his Newcastle debut so far but Benitez has not given up hope of his latest acquisition being ready in time for the visit of Jose Mourinho's side.
"Yesterday he did part of the training session and today he trained in the gym so we will have to see how he feels tomorrow," Benitez told a press conference on Friday, Sky Sports report.
Providing an injury update on the rest of his squad, Benitez added: " [Jesus] Gamez is getting better but still we have to wait. [Mohamed] Diame is training. [Ciaran] Clark is training after his knee problem," the Chronicle report. "Slimani has been part of the training session so we will see. We have to see if he is feeling tomorrow to see if he can start. Joselu fine too."
Newcastle have not won on at St James' Park since last October with their inability to turn draws against the likes of Swansea City, Burnley and Brighton into wins seeing them slide down the Premier League table, with the north east club currently sat just a point clear of the relegation zone.
"In terms of results it has not been good, but sometimes we have deserved more," Benitez said. "We have to learn to score the second goal & manage things a little better. Our idea is to win every game, home or away, and we have to learn to do that quickly."