Malcom's difficult start to life at Barcelona continued after he was axed from the squad for Saturday's game against Rayo Vallecano amid reports he wants to leave in January.
The Brazil forward made his first start of the season against Cultural Leonesa in the Copa del Rey this week, but was substituted before Barca's late winner after failing to make an impression.
Midfielder Carles Alena -- whose first appearance of the season came against Cultural as a sub -- takes his place.
Asked whether he was sending a message to Malcom, Barca coach Ernesto Valverde told his prematch news conference that "it's a message for Alena, who is doing well and can help us."
Malcom, 21, had been set to join Roma from Bordeaux in the summer before Barca tabled a €41 million bid. However, amid debate about whether Valverde backed the signing -- he has referred to him as "the club's signing" -- Malcom has found it hard to break into the team.
Before starting against Cultural he had played just 25 minutes, spread over substitute appearances against Real Valladolid and Leganes.
Mundo Deportivo reported earlier in the week that Malcom would ask for a move in January if things did not change, something both player and club denied.
Several English clubs are reportedly monitoring the situation, while Roma have also been linked with another move for him.
Meanwhile, Barca will be without Lionel Messi at the weekend despite his return to training on Wednesday, 10 days after breaking a bone in his arm against Sevilla.
Valverde would not confirm when Messi would be available again when asked if he could be included in the squad for Tuesday's Champions League game at Inter Milan.
"It was an arm injury so it's normal that he's back training quickly, so he can keep in shape," the Barca coach said.
"But we're going to wait. It's only two weeks since the problem, it's soon, so we still have to wait.
"The team's form is not making us more cautious, what's making us cautious is the injury he has. If he was ready [for Rayo], he would be there and we'd be stronger -- he gives us that differential factor. We want him back. We're better with Leo."
Barca have regained top spot in La Liga after going four games without a win before the international break but Valverde warned that they would need to be switched on to beat Rayo.
"The Leganes [defeat] is a reference," he said. "We don't want to make the same mistake. It's in games against sides not like last week's opponents [Sevilla and Real Madrid] when we've had the most problems."