Liverpool have won their first four Premier League games of the season and sit top of the table.
The Reds have conceded just one goal so far this term, with that coming from a huge error by goalkeeper Alisson.
Alisson was one of four new players who joined in the summer as Jurgen Klopp splashed out around £175million on new talent.
Thompson has been seriously impressed with the Liverpool defence and says that has been the key to their fine start to the campaign.
The Sky Sports pundit is slightly concerned Liverpool’s intensity has dropped off in second half of games though.
And Thompson also says the front three of Mohamed Salah, Sadio Mane and Roberto Firmino are yet to fully fire, despite scoring seven goals between them so far.
“We’ve had an absolutely fantastic start to the season,” Thompson said on Sky Sports News.
“You look at it, very good against West Ham, then decent against Crystal Palace. Then you had Brighton and Leicester.
“The levels and the intensity has been going down, particularly in the second half of games.
“Although it’s been great, it’s that expectation of where this Liverpool team is going to go.
“They will be a massive threat this year.
“I think the front three haven’t really got going, so why has it been so good?
“I really think the defence has been quite excellent and I think that is the benefit.
“Maybe the front three are thinking ‘we’re alright now, we don’t have to score three and four in the first half, we can actually rely upon this back four and this goalkeeper to bail us out at times’.”
Liverpool will look to make it five wins from five in the Premier League on Saturday when they visit Tottenham (12.30).