Recent changes in English football's hierarchy have left Manchester United unable to exert their traditional dominance in the transfer market, according to manager Jose Mourinho.
For much of the 1990s and throughout the early 21st century, the Red Devils were able to acquire some the sport's biggest stars at will.
After a brief lull in spending late in Alex Ferguson's tenure, United broke the world transfer record to re-sign Paul Pogba from Juventus in 2016, as well as making significant outlays to acquire Romelu Lukaku, Nemanja Matic and Fred in recent seasons.
But Mourinho feels the time when they could take their pick of the standout talents at domestic rivals is over.
"It depends," he told a news conference when asked if expectations at United are different from other clubs.
"I will give you an example, that I hope is a good example. I hope you can interpret it in the right way.
"Is Manchester United by history, by its dimensions, bigger than Tottenham? With all the respect - Tottenham is an amazing club - I think everybody would say yes.
"Can we go to Tottenham and buy their best players? No - because they don't sell or because they are so powerful that they can say no.
"A few years ago, who was Tottenham's best player? Michael Carrick. A few years later, who was the best player? [Dimitar] Berbatov," he said, referring to two Spurs stars lured to Old Trafford during Ferguson's reign.
"Can we go now there and bring Harry Kane, Dele Alli, [Christian] Eriksen, Son [Heung-min]?
"Can we go there and bring the guys here? No.
"So, who is more powerful now. Them or us?"
Mourinho also appeared to refer to the financial might on show at local rivals Manchester City, who have repeatedly parted with sizeable transfer fees to equip coach Pep Guardiola with the squad that cantered to the Premier League title last season.
"Football changes," the Portuguese said. "It is more difficult to buy players of a high, high, high level.
"The clubs are more powerful and don't want to sell.
"Before, the smaller clubs, they were almost begging the big clubs, 'get my best player, I need to sell. Please, you are powerful, buy my best player'.
"At this moment, they don't want to sell.
"It is more difficult to make the team better and stronger with buying.
"Unless you do what some clubs do, and for some reason they can do and others cannot.
"Which is, I need a right back and a left back. Send away the ones you have and buy four at the same time.
"It is difficult, so we do what we can.
"Last season was fantastic to finish second and we are fighting hard. I know we have to do better than we are doing.
"But one thing is to do better and another thing is to try and compare ourselves with what Manchester United was in the past.
"Not just because Manchester United was fantastic, but because there was a big difference to the others and, at the moment, it is not like that."
United are away to struggling Southampton in the Premier League on Saturday.
