Jorge Sampaoli's side head into their final match in the South American section with their chances of reaching next year's finals in Russia hanging in the balance.
Ecuador have lost their last five qualifiers and are already out of contention for the top five, but Argentina, who have drawn three games in a row and scored only one goal in that time, have not won in Quito since 2001.
However, Menotti, who guided Argentina to their first World Cup triumph in 1978, believes Messi can be the man to make the difference on Tuesday.
"To have Messi in the team is to have someone who can save you," he told TyC Sports.
"It's not ideal that it works like that, but it's how it is.
0,94 - Argentina have their lowest goal average with only one game left in WC Qualifiers (actual format). Misfortune. pic.twitter.com/nesBIuRFIO— OptaJavier (@OptaJavier) October 9, 2017
"Having Messi is a bonus that can save you at any moment. Football is about order, but also adventure.
"It would be frustrating for the other guys not to see Messi at the World Cup, not only for himself.
"Seeing Messi at the World Cup with the national team has become something cultural. Leo has magic, like [Diego] Maradona."
Argentina have only won six matches in a turbulent campaign in which Sampaoli replaced Edgardo Bauza as coach in a bid to revitalise their fortunes.
Menotti says there is no point trying to assess what went wrong until after the Ecuador game, though.
"The team are obliged to qualify," he said. "There's no time left to understand the things that have gone badly."