The Women's Super League (WSL) is investigating Crystal Palace after the newly promoted side used four substitution windows in their season opening 1-0 win over Everton on Sunday.
A statement from the league said that Palace "breached" the rules, with the regulations only permitting a maximum of three substation opportunities per match.
Summer signing Lexi Lloyd-Smith struck in the 34th minute with the only goal of the game.
The Eagles used their three separate substitutions at the 62nd, 83rd, and 90th minute before manager Jo Potter brought in Kirsty Howat in the 97th minute during 13 minutes of stoppage time.
There is no automatic punishment for a substitution rule break however, the club could face a points deduction or be forced to replay the game if the situation is referred to an independent tribunal.
They could also face no repercussions if it is found that the officiating team were at fault. Sources told ESPN that the team of officials will not be appointed for the next round of games while the investigation, involving both clubs and Pro Ref (formerly PGMOL) is ongoing.
Referee Megan Wilson has been officiating in the WSL since 2023 and has overseen over 45 games across the top two tiers and Cup competitions.