Real Madrid will have to make do without key forward Kylian Mbappe, who did not travel to Charlotte for the team's Club World Cup match against Pachuca.

He could, however, be back for the final group-stage game, coach Xabi Alonso said on Saturday.

The French superstar was taken to hospital on Thursday for tests and treatment after suffering gastroenteritis, before later being released.

"Mbappe is improving "bit by bit," a club source told AFP, but he did not fly with his teammates for Sunday's match against Mexican side Pachuca.

Real boss Alonso addressed the striker's condition during his pre-match press conference.

"He's doing better, he's back from the hospital and is recovering. We're optimistic about having him against Salzburg," he said.

Madrid face Salzburg in the final game of group H on Thursday in Philadelphia.

The 26-year-old missed the opening game with the same illness as Madrid were held 1-1 by Al-Hilal in Xabi Alonso's debut as coach.

Madrid B-team player Gonzalo Garcia, 21, started in Mbappe's stead and opened the scoring for Real Madrid against their Saudi Arabian opponents.

Alonso indicated that Gonzalo would again deputise for the Frenchman.

"Gonzalo can do what he did the other day. He scored a goal and had three chances. Looking ahead, we'll see what happens. Having players with that sense of smell is very important. He did very well," he said.

Mbappe finished as the European Golden Shoe winner in his first season at Real Madrid with 31 goals in LaLiga and 43 across all competitions, but Los Blancos finished the season without a major trophy.