The French superstar believes he was sidelined by PSG and made to train with players the club were trying to offload after refusing to agree a new contract.
New head coach Xabi Alonso will make his debut on the Real bench for the Group H match at Hard Rock Stadium and could be without several regulars.
Mbappe has repeated his desire to win Europe's biggest club competition, but the closest the Paris-born forward got with his boyhood club was losing the final in 2020 to Bayern Munich.
After the Catalans scraped a comeback win at Valladolid on Saturday, Madrid survived a late Celta fightback to maintain the four-point gap ahead of next Sunday's Clasico.
Mbappe idolised Ronaldo while growing up and after joining Madrid from Paris Saint-Germain last summer, has equalled the Portuguese striker's tally of 33 goals in his first season at the Santiago Bernabeu.
Mbappe's double took him to 33 strikes in 44 appearances across all competitions, the same number of goals as his idol managed in the 2009-10 campaign.
The French superstar did not train with his team-mates on Tuesday ahead of the game but coach Carlo Ancelotti said the striker would travel to San Sebastian.
The Italian coach said that he was never in doubt that the 26-year-old forward was going to find his form despite a slow start in the Spanish capital after arriving from Paris St Germain, playing in a more centralised role up front.
Speaking on a podcast hosted by former Brazil striker Romario, Neymar blamed a clash of egos for the failure of the three stars to gel during their spell together at the French club.
Kylian Mbappe said Liverpool were one of the clubs he spoke to before deciding to extend his stay at Paris St Germain, and that he had also met with the Premier League side in 2017 when he was still at Monaco.
France forward Kylian Mbappe said he "can imagine" Real Madrid's disappointment after rejecting them to sign a contract extension with Paris St Germain, adding that he will be supporting the Spanish side in the Champions League final against Liverpool.
Kylian Mbappe's decision to stay at Paris Saint-Germain confirms the Qatar-backed club's position of power within European football but also means the superstar striker is likely to wield huge influence as they rebuild for another assault on the Champions League.
All eyes were on the Parc des Princes for the announcement that Mbappe had signed a new three-year deal with the French champions, who demolished Metz 5-0 with the France forward scoring a hat trick to finish Ligue 1 top scorer with 28 goals.
Paris Saint-Germain's extension deal with Kylian Mbappe is "an insult to football," La Liga president Javier Tebas said Saturday after the player reportedly rejected an offer from Real Madrid.
The two most expensive players in the world were unable to outshine the prolific Erling Braut Haaland as the Norwegian sensation continues his remarkable rise by scoring both goals in Borussia Dortmund's 2-1 defeat of Paris Saint-Germain in their Champions League first-leg encounter
Kylian Mbappe scored two goals in four second-half minutes to send France into the World Cup quarter-finals with a thrilling 4-3 win over Argentina on Saturday.
Pep Guardiola confirms Manchester City are "still looking" to add to their £200 million summer spending spree, although he refuses to comment on the possibility of hijacking Real Madrid's move for Kylian Mbappe.
