Granada appointed former Atletico Madrid boss Abel Resino as their new boss earlier this week following the dismissal of Fabri Gonzalez.
Fabri led Granada to back-to-back promotions - including a berth in the top flight for the first time in 35 years - but he was sacked after a run of four defeats in their last five Primera Division matches saw them drop into the relegation places.
With Betis climbing back up the standings with a 10-point haul from their previous five fixtures, the Seville-based side would have been confident of adding to Granada's woes tomorrow, but Mel concedes that may no longer be the case.
"The game is difficult because we don't know which Granada we are going to find," he said.
"A change of coach always sparks the players and now everything we thought we knew about them has to be thrown away because it's worthless. With Fabri we knew what sort of team would be visiting us."
Granada's last three matches has seen them concede 10 goals in losing to Real Madrid, Rayo Vallecano and Espanyol, but centre-back Manolo Lucena is nevertheless optimistic they can pick up a good result from their trip to Betis.
"We are good enough to get something positive from Betis. We know we didn't get enough points in the first half of the season but there is the quality to improve the situation and be able to achieve our final goal of survival," he said in the Spanish press.