The Tunisian African champions were beaten 1-0 by the 10 men of Argentine giants Boca Juniors, who now go on to meet either AC Milan or Japan’s Urawa Reds in the Final.
Etoile will play the losers of that game in a third-place play-off on December 16.
The only goal of the game came in the 37th minute when midfielder Neri Cardozo steered the ball home, though Gabriel Paletta and Martin Palermo could have made the margin of victory more comfortable had they not been so wasteful in front of goal.
The South Americans lost Fabian Vargas to a second yellow card on 65 minutes, but managed to withstand the pressure from Etoile in the closing stages.
"We still dominated with 10 players and created a lot of chances. Milan must beat Urawa first but if we face them we will need to improve, particularly in midfield," Boca coach Miguel Angel Russo said after the match.
Despite the defeat, Etoile coach Bertrand Marchand was happy with his players.
"We played one of the best games in our history," he said Etoile's French coach Bertrand Marchand. "Boca are one of the world's top sides and we gave them a difficult game. They have the quality to score goals out of nothing – different class. One bit of magic won the game."