It's a puzzle for beaten Liverpool without missing pieces

Liverpool's 1-0 defeat by Aston Villa on Saturday was more than an early season setback – it raised the question of whether they have the strength in depth to cope with the dual challenge ahead of them this term.

For the first time in four years Liverpool are back in the Champions League and much of the focus of their transfer market strategy has been based around creating a squad big enough and good enough to be able to fight on two fronts.

With a home game against Bulgarians Ludogorets to come at Anfield on Tuesday, manager Brendan Rodgers decided to introduce his first squad rotation of the season – albeit a modest one.

Lallana makes his debut for Liverpool

With Daniel Sturridge being injured on England duty, Rodgers decided to leave Raheem Sterling on the bench and hand Adam Lallana his debut to provide support for lone striker Mario Balotelli, with Serb Lazar Markovic given his first Premier League start in midfield.

Rodgers has options especially in attack. Even without Sturridge he could afford to put England international Rickie Lambert and Italian Fabio Borini on the bench and both were introduced late in the game as Liverpool desperately sought a goal.

"It is down to everyone," the manager told reporters. "The squad that we have here is a very good squad.

"We are unfortunate to be missing one or two but we have still got enough quality in our depth to create that wee bit more and have more efforts on goal."

Agbonlahor guided home the winner

Villa took a ninth-minute lead when Philippe Senderos headed down an Ashley Westwood corner and Gabriel Agbonlahor hooked the ball in from four metres.

The early goal put the onus on Liverpool to create but they found it difficult to open up a well-marshalled visiting defence.

There was no disguising the fact the hosts missed the strike pairing of Sturridge and Luis Suarez, who is now with Barcelona, that brought them 56 league goals last season.

Lacking pace

However, Liverpool also lacked the pace, invention and directness that Sterling and Sturridge have brought.

Balotelli coped well with some defending, from Senderos in particular, that at times looked to be testing his ability to avoid provocation, but the Italian is at his best when he has others stretching the defence and creating him space.

Too often he was left isolated and too often Liverpool's forward movement was predictable.

If the new faces looked like they still needed to go on Liverpool's orientation programme, Aston Villa manager Paul Lambert will be delighted at the way Tom Cleverley, a deadline-day loan signing from Manchester United, fitted into a talented midfield alongside Fabian Delph and Kieran Richardson.

Liverpool's squad rotation will be a challenge this season

With 20 minutes left and no sign of a change of momentum, Rodgers threw on Borini and Lambert but it was Brazilian Philippe Coutinho who almost salvaged a point with a shot against the post in the 82nd minute.

It was a second league defeat in four games this season for Liverpool and while Rodgers was keen to give second-placed Villa deserved credit, he was also smart enough to know where his problems originated.

"Normally we are a team that start very fast with a high-level tempo, for some reason we didn't start like that and sometimes when a good team gets in front it is hard to break them down," he said.

Finding a way to be a high-tempo threat without Sturridge and Sterling seems to be the key to Liverpool's squad rotation challenge this season and judging by Saturday it might be easier said than done.