Not enough money has been spent, says the Portuguese, who has seen three players added to his squad over the summer - Brazil midfielder Fred for $60 million, Portuguese defender Diogo Dalot ($24 million) and third-choice goalkeeper Lee Grant ($2 million).
"I am still expecting them to be very strong this season, and I actually think that, along with Liverpool, they will be a lot closer to Manchester City this time".
However, former Newcastle striker and the all time leading Premier League goal scorer Alan Shearer thinks that Mourinho's whinging is unwarranted, and his side will be a force to be reckoned with.
"So I will have to focus on the players I have and in relation to these first couple of matches - maybe three matches because after Spurs (and Burnley on August 27 and September 1 respectively) there is (a) national team (break) and a couple of weeks to recover people and prepare people better".
Liverpool had to spend big to give Klopp a chance to compete with Manchester City in the Premier League and to have another go at winning the Champions League and I applaud the club and the manager for showing real ambition ahead of this new season. I don't think just because they haven't signed a centre-back we should be sat here thinking "We'll let Manchester United off the hook, they shouldn't be challenging this year".
"Subject to any late sales, the Premier League and its clubs may benefit from having playing squads settled and in place for the start of the new season".
Sergio Romero, Valencia, Marcos Rojo, Dalot, Ander Herrera and Matic are all injured for Leicester's visit, while Mourinho needs to check on the fitness of those that returned late from the World Cup. The way in which United are being talked about this pre-season, it's as if they've got a load of bums playing for them.
As far as the rest are concerned, Paul Pogba, Jesse Lingard, Ashley Young and Marouane Fellaini are very unlikely to feature as they only returned to training on Monday. "They trained on Monday, Tuesday, Wednesday and today, so you can imagine that they're not really fit and ready, but we have needs", said the boss of the quartet.
"So it's hard for me to understand or to feel or to believe that we finished second, which I keep saying that I - and sometimes it's also hard to believe - that I won eight championships and three Premier Leagues".
But Liverpool have won the last four meetings between the two sides, albeit only one of those was in the Premier League.