Madrid are second in the table with their title hopes over, but in good form and preparing for a Champions League semi-final date with Borussia Dortmund.
Betis are no pushovers, though, and are chasing a European berth for themselves next season.
They are currently seventh and will be buoyed by their comeback from 3-0 down to draw with Sevilla last time out.
"It is a tough game that everyone takes for granted that we will lose," Mel told his club's official website.
"We will try and show the options we have, though."
Despite the meek surrender of their title, Madrid have been a formidable outfit in 2013.
A weakened side beat Barcelona and, with the Champions League at the forefront of their minds, they may choose to shuffle the pack against Betis.
But regardless of who plays, Mel knows his men have a challenge to face.
"This year no team has won at the Bernabeu and it is not going to be easy," he said.
"Madrid do not give anything away to any team because they are hugely competitive.
"We cannot help who plays. If it is not (Mesut) Ozil it will be (Luka) Modric. They are all very good.
"No matter who plays it will be very complicated and we will have to be careful not to leave space."
Madrid coach Jose Mourinho, who has once again been the subject of intense speculation this week, has perhaps given a hint of what he is thinking about tomorrow's game.
His club's official website have reported that Castilla players Alex and Casemiro - both midfielders and the latter a loanee from Sao Paolo - have been training with Mourinho and his first-team this week.
Although he has not publicly said he will be leaving the club in the summer, reports have continued to indicate Mourinho will be seeking a new challenge come the end of the campaign.
A coach at the youth club Canillas, where Mourinho's son plays, told Spanish newspaper AS that the Portuguese had told him he was heading back to Chelsea.
Either way, Madrid have two trophies left to fight for, starting with the Champions League as well as the Copa del Rey.
Betis have things to achieve too. They are currently outside of the top six but, with fifth-placed Malaga currently banned from playing in Europe next season, they are in pole position to capitalise.
They have a four-point cushion over eight-placed Getafe, while Madrid are 13 points shy of Barca.