Former Liverpool pair Joe Cole and Peter Crouch feels they need to make a big money signing.
Jurgen Klopp's side have undergone another relatively quiet window so far with Ibrahima Konate the only new face in the Reds squad after the defender moved for £36million from RB Leipzig.
Crouch told BT Sport before their match with Burnley: "When a new signing walks through the door, when Lukaku. Sancho and Varane walk through the door (it lifts everyone). If they (Liverpool) signed Lukaku, you're talking about them being front runners for the title.
"They haven't signed anyone, they've got Konate but they haven't really gone out and got someone. This squad still has the quality to be title contenders.
"When someone walks through the door, when Shevchenko and Ballack walk through the door, when Torres walks through the door, it lifts training.
"But with van Dijk, when the full-backs bomb forward when the strikers bomb forward, when they look back and see him there it's a big lift to the whole team."
Cole claims Klopp's side are relying on the group of players who earned them the 2019-20 Premier League title, without having to change too much from external investments.
"I wouldn't say I'm concerned. They didn't do any business last year, they are banking on that unit of players that won them the title.
"Last year, it got decimated by injuries. Instead of going for the big star, we're going to put you in that position on the pitch and challenge Mane. They've gone around the peripheries, while Chelsea have gone 'Lukaku, he's playing. If it upsets Havertz and Werner, whatever'.
"Whether they have the money to go for big players, I don't know. They've gone down the road of giving out big contracts."