Former Liverpool defender Steve Nicol says he "couldn't understand" why Jurgen Klopp did not play Joel Matip in the centre of defence during Saturday's 3-2 loss to Swansea City.
Matip had missed Liverpool's two previous games due to uncertainty over his eligibility after he declined to play for Cameroon at the African Nations Cup but, although FIFA said he was free to play against Swansea, he was only among the substitutes.
He finally made his introduction in the 94th minute as a replacement for Georginio Wijnaldum and was used as a makeshift attacker.
"There was one thing that I couldn't understand that happened in the game," ESPN FC analyst Nicol said. "Liverpool's best defender, Matip, was sat on the bench. Why? And when he came on, he played centre forward. He's sitting on the bench.
"For two weeks we've been moaning about 'Oh he can't play because he's supposed to play at the Africa Cup of Nations' and all of a sudden he's not starting the guy. Why is he on the bench? He's the best defender.
"He's the guy that's really held them together, in my opinion, when he's played and he doesn't start. It makes no sense. Liverpool are fantastic going forward. Jurgen Klopp, no question, knows what he's doing going that way, but there has to be questions about what's happening defensively."
Klopp selected Ragnar Klavan alongside Dejan Lovren at centre-back for the match, with Nathaniel Clyne at right-back and James Milner continuing in his new left-back role.
"We shouldn't be surprised the way they lost the goals," Nicol, who joined the Reds in 1981 and left in 1994, added. "Obviously, you don't expect them to lose them against Swansea but it's the way that they lost them that we shouldn't be surprised about, because the basic defensive principles [are ones] Liverpool can't do.
"It's not about getting the team on the training field and coaching them. You can spend all day with your shape and everything else. When it comes down to defenders in the game making decisions, there's nothing you can do about that. Liverpool don't have players defensively who make good decisions."
Liverpool have taken only two points from their three league games since the turn of the year and are now fourth, 10 points behind leaders Chelsea, but Klopp has suggested January signings are unlikely as clubs are rarely willing to sell quality players in midseason.
"I don't see Liverpool winning the Premier League title with the defence they have," Nicol, who won five league titles with Liverpool, said. "They don't look as if they are going to bring anyone in this window, which means they've got what they've got.
"When they let in goals that they have done -- not just at Swansea, against Burnley -- [they are] perfect examples that it's not happening. Bournemouth -- four goals at Bournemouth. A team doesn't win the Premier League shipping goals in the way they do."