Souness told the Sunday World: “We all thought it would be Guardiola v Mourinho doing battle at the top of the Premier League last season, but these two great managers never even came close to getting into the title mix.
“In the end, Guardiola and Mourinho were comfortably overshadowed by Antonio Conte at Chelsea and Mauricio Pochettino at Tottenham, so they will be under big pressure when from day one next season because they are working for owners who expect to be challenging for the title.
“The record these two guys have confirms they are great managers, but they have probably taken on the biggest challenges of their career in these two jobs and it remains to be seen whether they are up to the task.
“For City to finish as far behind Chelsea as they did last season was a surprise because they were great in the opening games games of the season and then faded badly.
“As for United, they did well in the cup competitions, but United expect to be in the top four of the Premier League and all we got from Mourinho for most of the season was moaning and groaning and excuses.
“Manchester United is a massive football club and they have resources to make sure they can have no excuses if they pick up a few injuries or have a lot of games.
“If you want to win trophies and play in lots of competitions, then you are going to have a lot of games at the end of the season, which should be seen as a good thing.”