Iran drew 0-0 with 10-man Belgium as World Cup Group G became even tighter on Sunday.
The Red Devils had defender Nathan Ngoy sent off for a last-man foul on Iran's Mehdi Taremi following a woeful back-pass on 66 minutes, but a stalemate remained and set up two crucial group finales.
Iran earlier thought they had taken the lead following a clever free-kick routine, but Taremi was deemed to be offside after a long video review.
Thibaut Courtois was also forced into two smart stops but otherwise Belgium dominated possession and chances, although they could not break through as Iran's defence put their bodies on the line.
In Belgium's 1-1 opener with Egypt, forward Romelu Lukaku had helped force the equalizer 22 seconds after climbing off the bench.
He was rewarded by Rudi Garcia with a start against Iran, his first for club Napoli or country since June last year following an injury-ravaged season.
But the 33-year-old and his fellow remaining veterans from the "Golden Generation" - who finished third in 2018 - looked short of ideas and need a win against New Zealand in the group decider on Friday.
Winger Jérémy Doku missed out through illness and may leave the camp at some point if his partner goes into labour.
Iran started the tournament with a 2-2 draw with New Zealand - in the same stadium in Inglewood, Los Angeles County.
For these two games, Iran have had to travel from their headquarters in Mexico to the US less than a day before the game.
For the group decider against Egypt in Seattle on Friday, they have been given more leeway by US authorities given a slight easing of tensions between the warring nations.
