Liverpool manager Brendan Rodgers said his team are in a period of "transition" and will face more "pain" before they start to turn the corner.
Last year's runners-up have won only two of their first six Premier League matches and lost 1-0 to Basel in the Champions League on Wednesday.
Rodgers said: "We had to improve the squad and unfortunately we've lost a number of our key players to injuries.
"It brings us into a little period of transition again."
The departure of Luis Suarez to Barcelona and an injury to Daniel Sturridge has deprived Rodgers of a strike force that scored 53 league goals between them last season.
In their absence, new attacking signings Mario Balotelli, Lazar Markovic and Adam Lallana have struggled to make an impact, with the Reds scoring only eight times in six league matches.
There have also been problems at the back, with just one clean sheet in nine games this season.
|Liverpool's last six games|
|FC Basel 1-0 Liverpool|
|Liverpool 1-1 Everton|
|Liverpool 2-2 Middlesbrough (Liverpool win 14-13 on penalties)|
|West Ham 3-1 Liverpool|
|Liverpool 2-1 Ludogorets Razgrad|
|Liverpool 0-1 Aston Villa|
Rodgers compared the unsettled situation to the one he inherited two years ago before the team set off on a "magic carpet ride".
Asked if he was facing the biggest challenge of his managerial career he replied: "No, not really. It's an exciting challenge. This is an incredible job and nothing has changed.
"The first six months were difficult here but for 18 months we've been on a magic carpet ride in terms of our performance level and everything improving.
"For me it would have been a case of keeping the squad we had and adding a few bodies to thicken up the squad.
"But that wasn't the case. There was big change here in the summer and we lost a world-class player (Suarez)."
On coping with the transition, he added: "It's something that was difficult in the first few months when I got here.
"You have to go through some pain along the way. We are in a difficult moment but that's the great challenge for myself and the players."
Rodgers said the return from injury of players such as Sturridge and midfielders Emre Can and Joe Allen would give him more "flexibility" in tactics.
Allen's absence through a knee injury has been particularly costly, he said.
"He's a player who never gets mentioned but he's a player who rarely turns over the ball," Rodgers added. "He loves the football and gets other people playing.
"The key feature for Joe on top of that is the intensity in his pressure. He's an intelligent footballer. Tactically he's outstanding and we've really missed his energy and his quality since he's been out."
Allen is expected to be fit to face QPR on 19 October.