Tuesday 17 April 2018 13:58, UK
Gary Neville insists it is "going to go off" between the two Manchester sides in the next 12 months with Pep Guardiola and Jose Mourinho in search of more silverware next season.
Both managers have 20 career titles to their name after United's 1-0 defeat by bottom club West Brom on Super Sunday handed rivals City the Premier League title.
Neville, speaking on Monday Night Football, thinks the two managers are on a collision course next season as they look to add even more silverware to their highly decorated CVs.
"When they both came in Manchester two years ago this was going to be a collision course," the former United defender told Monday Night Football.
"There was always going to be a winner and a loser. If you look at the head-to-head of these two managers and the titles they have won, they have won 20 titles each.
"If Manchester United were to win the league next season, Jose Mourinho would say that he's come out on top over the three years period. If Pep Guardiola wins the title next season he will say he is starting to dominate English football and produce a great side, saying his team are the winner and he is the winner so next season is critical.
"This season there is no doubt that Guardiola has stolen in front. Mourinho can still end the season with a trophy to add to the two of last season, so you can't say he's been a failure but over a three-year period, it's who wins the Premier League titles that will come out the winner.
"Next season is absolutely critical for both managers."
While Neville admits Guardiola has gone ahead of his rival after winning the title this season, he is expecting Mourinho to come back even stronger next season.
"Guardiola is not going to let up but Mourinho has also never given in so this is going to come to a head," he added.
"This time next year we will be talking about who is the winner and the loser in Manchester because this is a massive collision course.
"This is going to go off at some point in the next 12 months, I can assure you of that and for United fans, they'll hope they can come back and for City fans, they'll hope they can just drill United into the ground and finish them off."
City secured a third title in seven seasons with five games to spare and find themselves three wins away from securing a record points tally of 96.
They could also break the record for the most matches won in a Premier League season and the goals record too if they come even close to maintaining the current rate, and Neville was full of praise of the way City have gone about their work this season.
He added: "In terms of style I had my doubts from last season. Every Premier League team that I've seen win the league has had an element of what I call power. There's never been a team that I would say in my mind that played just pure football.
"Of course they've had to defend free-kicks, of course they've had to do the ugly part of the game at certain points but they've absolutely shown us another way. I look at the possession of the teams that have won the league that is a different level.
"In terms of style, this is different to anything we've seen before. Of course we have seen teams keep possession. All the teams that have won the league, apart from Leicester, have had more possession but to get to a 70 per cent average is absolutely outrageous."
