Benitez reportedly tested positive for cocaine earlier this week, with club president Quique Pina later announcing the player will be sacked once they have official confirmation from the relevant authorities.
Alcarez voiced his disappointment over the news, but remains confident it will not affect his team in their match against mid-table rivals Levante on Monday.
"Of course it is sad news and it is not a pleasant issue," he told a press conference. "But we have to put it to one side as we have a match on Monday.
"Monday's game is the kind of match in which we would like to take three points. The team will play with enthusiasm, motivation and are super-psyched.
"Levante are a strong team, well organised and well managed who will make things difficult for us, so I expect a close contest."
Granada saw a three-match unbeaten run ended by a 1-0 defeat to Primera Division leaders Atletico Madrid on Wednesday, but Levante will be the team with a point to prove after losing 3-1 to basement side Real Betis.
The Valencia club have not won in four league fixtures and will start Monday's match just three points better off than their 12th-placed opponents.
Coach Joaquin Caparros said: "The team have not been playing at the level they should be.
"There are eight matches left and we have to fight for every point. Hopefully, our next league match on Monday will take away the bad taste left by the Betis defeat."
Andreas Ivanschitz has returned to training with Levante following an adductor injury but there are doubts over the fitness of David Navarro (ankle).