Paulo Bento's side are one point behind Russia, but the leaders will be expected to take maximum points from their final matches against Luxembourg and Azerbaijan.
Victory over Israel in Lisbon on Friday would at least ensure Portugal finish no lower than second, and they could still progress through the play-offs without overhauling Russia.
"I am confident in the victory," he said. "They are two games we have to win, we are the favourites and we will get on the field and give the best to ensure the six points.
"We just have to win both games and see what Russia does."
"All players play in big clubs and know the responsibility of playing in the national team. Missing two games and not winning is not worth thinking about," the Real Madrid star added.
"We have the better team and we need to show that on the field; we have a great chance to win the game."
In contrast, Israel’s last victory came back in March and they were beaten by Russia last time out.
The previous group meeting between Portugal and Israel saw the former come from 3-1 down to snatch a draw through Fabio Coentrao’s late equaliser.
Meireles' absence, due to a problem with his right thigh, was confirmed on Wednesday with Custodio called up as a replacement.
