The trio were all in action when Liverpool drew 2-2 at Chelsea in the Premier League on Sunday.
Mane and Salah were on the scoresheet while Keita was a second half substitute at Stamford Bridge.
Liverpool might have to do without the trio for the next one month as they pursue Manchester City for the Premier League title.
But Ljinders, who filled in for the coronavirus-infected Jurgen Klopp at Stamford Bridge, is backing others to step up to keep their title hopes alive.
"You can try to plan it, but you can never prepare it," he said.
"It is not a worry because we have faith in the boys we have and a few boys are coming back as well.
"We know that certain players can play more offensively as well, they have been playing in midfield, but they can play more offensively as well."
"I just told the boys that they should try to win the AFCON because it is a prize to catch and the careers are never long and they deserve to fight for each prize," Lijnders added.
"This prize now comes in front of them – it’s a tournament with so much passion, so much culture and it is a really proud situation if you can play for your country.
"If it's England or Germany or Holland or whoever, that's what they have and feel.
"So they are African legends, they are legends for me, but if they win it they will probably be even bigger legends so they should try with all they have to win it."
