Fifa has confirmed it has received an official protest from the Benin Football Federation (FBF) over its 2-0 loss to DR Congo in World Cup qualifying.
"Fifa has received a complaint from the Benin FA in relation to this matter and will review it," football's world governing body said in a statement.
"As per standard procedure, Fifa first needs to analyse the relevant match report reports before commenting. Please understand we cannot comment further at this stage."
The appeal is about the fact that DR Congo made four substitutions on four separate occasions during Sunday's qualifier.
Under current Fifa regulations for international games teams are allowed to make up to five substitutes but only during three windows in the game.
DR Congo won the tie 2-0 to progress to the African World Cup play-offs as winners of Group J instead of Benin, who had needed a draw in Kinshasa in order to advance.
"It is an appeal regarding the obvious violation of the laws of the game by the DRC," Benin's Sports Minister Oswald Homeky told BBC Sport Africa on Tuesday.
"The number and moments of replacement of players during a match is well known. The rules of the game are clear on that matter, and so we have a case here.
"The Benin Football Federation have asked Fifa to draw the conclusions and take the relevant measures of this obvious violation of the rules."
According to the match report on the Fifa website DR Congo made their first change in the 63rd minute, when they were leading 1-0. A further two substitutions were made after the second goal in the 77th and then 84th minutes before a final replacement came on in injury time at the end of the match.