Queens Park Rangers provisionally secured the Championship title with a 2-0 win away at Watford on Saturday.
Goals from captain Adel Taarabt and Tommy Smith at Vicarage Road secured a win that sends QPR eight points clear of second-placed Norwich.
Depending on the severity of the punishment – which could include a possible points deduction – they could yet lose the title and even fall back into the playoff places.
At the other end of the table, Scunthorpe’s relegation to League One was confirmed with a 5-1 thrashing away to Nottingham Forest.
Kris Boyd and Luke Chambers scored two apiece and Paul Anderson netted the other for Forest, who finished with 10 men after Robert Earnshaw was sent off in the 88th minute.
Forest, sixth on the table, are now three points clear of seventh-placed Leeds United and, barring a heavy defeat in the final round of the season, are likely to secure the last playoff berth.
Leeds defeated Burnley 1-0 in the early kick-off to keep their slim playoff hopes alive until next week.
Sheffield United will join Scunthorpe and already relegated Preston in the third tier after they could only manage a 2-2 draw at home to Barnsley.
Even if United had collected all three points at Bramall Lane, Doncaster’s 1-1 draw at home to Leicester would have consigned Micky Adams’ team to the drop.
In other matches, fifth-placed Reading drew 0-0 away to Coventry, while Swansea in fourth won 2-0 away to Millwall.
Hull City drew 1-1 at home to Crystal Palace, Ipswich beat visiting Preston 2-1 and Bristol City won 2-0 away to Derby County.
Norwich can secure automatic promotion on Monday with victory away to Portsmouth, but only if third-placed Cardiff lose at home to Middlesbrough earlier in the day.