The French superstar did not feature in the list of 23 players named by coach Xabi Alonso and published by the club for the match in Philadelphia, in which the two teams are targeting a place in the last 16.
Mbappe had returned to training on Wednesday after missing Real's first two matches at the tournament in the United States due to illness.
He was taken to hospital last Thursday for tests and treatment after suffering gastroenteritis, before later being released.
He played no part in Real's opening game, a 1-1 draw with Saudi side Al-Hilal in Miami, or the 3-1 defeat of Mexico's Pachuca at the weekend.
Alonso did indicate after the latter game that Mbappe was on the mend, saying: "He is doing better, he is recovering."
Real posted images of Mbappe in training on Wednesday on their website, as the squad worked out at their Florida base before travelling north in the afternoon to Philadelphia.
It is there, at Lincoln Financial Field, where Madrid will take on the Austrians in their final Group H match and will be looking for a victory which will confirm their progress to the last 16 in first place in the section.
A draw can also take them through to the next round, with Manchester City and Juventus the possible opponents in the last 16.
Mbappe has scored 43 goals in 56 appearances since joining Madrid from Paris Saint-Germain last year. His last game was for France in a 2-0 win away to Germany in the UEFA Nations League on June 8.
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