Mbappe missed the first three games of the tournament with an illness.
Alonso said Monday it was possible Mbappe could play in his first Club World Cup match in the knockout round, and the French star arrived with the team several hours before the game was set to begin at Hard Rock Stadium.
Mbappe had a gastrointestinal illness before Real Madrid’s opening Club World Cup match and was treated at a hospital. He sat out all three group matches as Madrid won two and drew the other.
He walked onto the field ahead of Tuesday's match to an ovation from the fans in the soggy venue that had seen downpours throughout the afternoon.
Mbappe's return brings star power to a tournament that took a hit when Lionel Messi and Inter Miami were eliminated in the round of 16 by Mbappe’s and Messi's former club, Paris Saint-Germain.
Madrid captain Dani Carvajal and defender Eder Militao were also set to return on Tuesday. Carvajal has not played since tearing his ACL and undergoing surgery last fall. Both were also listed as substitutes.
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