Southampton has been expelled from the Championship playoffs after admitting to repeatedly spying on opponents.The English Football League reinstated Middlesbrough to play in the Wembley final — the richest game in soccer — against Hull City on Sunday morning (AEST) Subject to the outcome, it could result in a further change to Saturday's fixture," the league said.The league said Southampton admitted breaches requiring clubs to act with the "utmost good faith and prohibiting the observation of another club's training session within 72 hours of a scheduled match."It said the final was still due to go ahead as planned, despite the disruption caused by Middlesbrough's late reinstatement.The playoff final is labelled the world's richest one-off soccer match because a windfall of at least $270 million in future earnings is on offer for the winning team.Promotion to the top flight of English football — the world's wealthiest and most-watched league — brings with it access to its multi-billion-dollar global broadcast deals as well as sold-out stadiums for games against the biggest teams in the world, like Manchester United, Liverpool and Arsenal.Southampton was relegated from the Premier League after finishing bottom of the standings last season and was aiming to make an immediate return.The stunning decision to expel it from the final comes after Leeds was previously punished for spying.In 2019, the EFL fined Leeds $259,000 for spying on one of Derby's training sessions ahead of a game.Marcelo Bielsa, who was manager of Leeds at the time, accepted responsibility for having a club employee spy on Derby's practice