Isco returned to full training at the start of the week after recovering from a back injury, but he will play no part in the crucial showdown with Barca this evening.
Solari has opted to leave the Spaniard out of the second-leg clash, with Madrid looking to build on a positive 1-1 draw at the Camp Nou in the first leg on February 6.
The Blancos boss has used Isco sparingly during his short reign at the helm, amid reports of a fractious relationship between the pair .
Isco has yet to start a single league game under Solari, with speculation swirling that the 26-year-old will leave the club at the end of the season.
Madrid have won eight of their last 10 matches across all competitions, but a 2-1 home defeat to Girona last week stalled their recent progress.
As a consequence of that result, they slipped nine points behind Barca in the Liga title race, but a 2-1 win against Levante on Sunday ensured that confidence was restored before their latest cup fixture.
Elsewhere, Solari has included Sergio Ramos in his final 20 to face Barca after the Blancos captain missed the trip to Levante due to suspension.
Despite his match-winning cameo during Madrid's last outing, Gareth Bale looks set to remain on the bench, with Vinicius Jr and Lucas Vazquez likely to play in a front three alongside Karim Benzema once again.
Madrid will, however, be without Marcos Llorente, who is still recovering from a groin injury.
Solari's men will be hoping to advance through to the final at Barca's expense and increase their chances of silverware this term, despite a difficult campaign post-Cristiano Ronaldo.
The Portuguese winger was sold to Juventus last summer and in his absence, Madrid have not carried the same attacking threat, but they are still in the hunt for a fourth consecutive Champions League crown.
Meanwhile, Barca come into the match with a renewed vigour, having beaten Sevilla 4-2 on Saturday to halt a slide which had seen them secure just one win in their previous five matches.
Full Real Madrid squad to face Barcelona: Thibaut Courtois, Keylor Navas, Luca Zidane; Marcelo, Raphael Varane, Sergio Ramos, Dani Carvajal, Nacho, Alvaro Odriozola, Sergio Reguilon; Toni Kroos, Luka Modic, Casemiro, Federico Valverde, Marco Asensio, Dani Ceballos; Vinicius Jr, Lucas Vazquez, Gareth Bale, Karim Benzema.