Jurgen Klopp's side finished fourth in England's top flight last season and have spent nearly £170m this summer.

They also paid £75m for centre-back Virgil van Dijk in January, but Adam says they need another defender to challenge champions Manchester City.

"Liverpool have done excellent business so far," he told BBC Radio 5 live.

Guinea midfielder Naby Keita has arrived from RB Leipzig for about £50m, Brazil midfielder Fabinho has joined from Monaco in a deal that could be worth more than £40m, and Switzerland winger Xherdan Shaqiri has come in for £13m.

Liverpool have also made Alisson the world's most expensive goalkeeper, recruiting the Brazilian from Roma in a deal the Italian club said is worth up to £66.8m.

However, the Reds have also raised significant funds, including through the £142m sale of Philippe Coutinho to Barcelona in January.

"Liverpool are one or two players from the title," said Adam on The Monday Night Club. "He [Klopp] has added quality to the squad, I still think they could do with another centre-half.

"They have brought Shaqiri in, a good replacement if Mohamed Salah needs a rest. Daniel Sturridge is to come back in - if he stays fit he could be in that team as well.

"The goalkeeper situation was a big problem for them last season. He has seen that problem and got that deal done," he said.

He [Alisson] is going to be worth six to eight points over the season. It adds a total belief and confidence."

New Liverpool signings Alisson, Fabinho, Keita and Shaqiri

'Shaqiri may get frustrated on the bench'

Shaqiri has arrived at Anfield from Adam's current club Stoke, and the Scot described the deal as "a great move" for both the Switzerland international and for Liverpool.

However, Adam - who spent the 2011-12 season with the Reds - has warned that the 26-year-old may get frustrated if he finds game time hard to come by under Klopp.

"He's got to try and replace Salah, the best player in the Premier League and has a chance for the Ballon d'Or," said the 32-year-old.

"It's only going to last six months and he won't be happy sitting on bench. He'll want to play in the bigger games.

"He might get frustrated at not playing as much as he wants - it's how long he waits and what Klopp does with him.

"He will fit in at Liverpool, he's a top player. He deserves to be there."

• Shaqiri scores overhead kick as Liverpool thrash Man Utd

Adam and Shaqiri were part of the Potters side relegated from the Premier League last season, and the midfielder feels the Swiss could have done more to aid the team's fight against the drop.

"He's a big player, at times he did well for us," he added.

"But in critical situations, I felt tracking back and what we needed for the team in a relegation battle just wasn't there.

"He has got it in him, but he probably knew we were going to get relegated, he was going to the World Cup and had this big move - this move was probably done three, four months ago.

"He is a match-winner, but at times it was difficult to play in the same team. The manager would let him get away with certain things. We fell short, it's not just him, there are others."

'We were told to be water carriers for Shaqiri'

Adam also said that former Stoke boss Paul Lambert suggested Shaqiri's team-mates were "water carriers" for the midfielder.

"He was the world-class player that we had in our team. Basically, we had to get him the ball to go and make something happen, which was difficult to take.

"We knew he was a match-winner, but we felt we should have had more respect from that point of view.

"When you have players that knew they were going to get a move whether they were relegated or not, it was inevitable what was going to happen.

"He felt Shaq was one who would keep us up - but we had others in teams who could win games."