Alonso has yet to feature this season after undergoing surgery on a broken metatarsal bone in August, but the Spain international is fit again and has been named in a 23-man squad for the match.
Madrid coach Carlo Ancelotti admits he is unlikely to start Alonso but is delighted to have the former Liverpool man back in the fold.
"He's available. He's training with the team and I think that tomorrow he could start on the bench, and I will try to give him some minutes," said Ancelotti.
"He has all the quality to help the team improve their play. He's got experience, is a quality passer and has a good defensive attitude. He's a very important player."
One player who is set to start on Wednesday is striker Karim Benzema, who was left on the bench for Saturday's match at Barca with Cristiano Ronaldo, Gareth Bale and Angel Di Maria taking on the main attacking responsibilities.
That move failed to reap any dividends though as Madrid struggled to create chances in the first half and only got on the scoresheet in the 90th minute as they slumped to a 2-1 defeat.
Ancelotti did not reveal who would make way for Benzema but confirmed the Frenchman would be brought back in.
"I won't say who'll play. One is Benzema, but the others I won't say," said the Italian.
"I want to rotate, these are all important games and we need to win them and gain confidence. I'd like to have the team motivated and in good physical shape. Rotations are good for that."
Madrid's loss at the Nou Camp left them six points adrift of leaders Barca in the Primera Division standings and, with Gerardo Martino's men going to lowly Celta Vigo on Tuesday night, they will be desperate not to lose any more ground on their bitter rivals.
Sevilla are unlikely to be pushovers though as they look to continue their improved form which has seen undefeated in their last seven competitive matches.
Ancelotti said: "They've gone five games in the league without losing and are very well organised. We must play with intensity from the first minute until the last. We must try to give our best and continue to improve our play.
"I hope tomorrow we have the intensity we were lacking against Barcelona. We only played well in the second half in the Nou Camp and we need to do that for the whole game."
Sevilla have climbed to 11th spot and are just three points off the European places following Sunday's 2-1 home win over Osasuna.
The Andalusian side have not won away in La Liga in over a year but full-back Diogo Figueiras sees no reason why they cannot end that run on Wednesday.
"Of course we can win at the Bernabeu as we've already shown against Barcelona (lost 3-2 away to a 90th-minute goal), where we had a great game, and we can win on Wednesday," he told SFC Radio.
"It's been a long time since we won away from home, but we are convinced we will win away."