Rafa Benitez fears both Albert Riera and Yossi Benayoun tore hamstrings in the 2-2 draw with Birmingham City.
Both wingers had to be withdrawn during a frustrating match which Liverpool dominated from start to finish.
Benitez said: "Riera had the same problem as before. The players are sometimes available but not 100 per cent ready. We thought he was okay but in the end you can see he wasn't.
"Yossi has the same problem as Riera. Some players are playing too many games in a row. They are working very hard and so you always have this risk. I think both will have tears.
"Agger also had a problem with his back. It's not serious but he felt it a little bit."
Meanwhile, Benitez revealed Fernando Torres didn't feel fit enough to play and so was left out of the squad.
"Torres had no confidence and said he couldn't play, so we started the treatment yesterday," said the boss.
"He has to work with the physios and try to improve and be ready. We are not talking about an operation at this moment, we're talking about treating him properly.
"I don't know if he will be ready for Man City (in two weeks). The only thing I can say is we're talking about two or three weeks working with the physios.
"We haven't got a deadline, we just need to see how he is every day."
There was better news to report on the returning Steven Gerrard, who was introduced just before the break to replace Riera.
"I think he will be okay," said Benitez. "We have to check. There's small things but I think he'll be okay."
Benitez felt his side deserved more than a point against Alex McLeish's men following an assured display.
David Ngog fired the Reds in front before Cameron Jerome and Christian Benitez gave Birmingham a shock lead.
Gerrard levelled proceedings from the spot but Liverpool couldn't convert a number of chances to clinch all three points.
Benitez said: "You have to be disappointed because it's a draw at home but the performance of the team was again pretty good, for me.
"We had plenty of possession and attempts, we showed character until the last minute. The fans were pushing. We couldn't get the third goal but we showed character.
"We had a lot of chances in the first half and it was unbelievable to see us losing 2-1 at half-time. We were attacking and attacking and I think we deserved to win.
"If you analyse the last games - against Lyon we conceded in the last minute twice, and then this game. You can't change the result but if you analyse you can see the team is doing well.
"The team is creating a lot of chances and sometimes you can't do any more. From the beginning we were on top of them. You didn't see a team that was thinking, 'Oh, we're playing badly.'
"For the last 15 minutes everyone in the stadium was thinking we'd score the third goal. Sometimes it's a question of accuracy and sometimes it's luck. We moved and passed the ball really well."
The result leaves Liverpool 11 points behind league leaders Chelsea.
Benitez added: "Since three weeks or a month ago I've been saying the same - take one game at a time. I will not talk about the table or position. We won six games in a row before and then played really well against United under pressure.
"The reaction of the players has been fantastic - the only thing we couldn't do is get the three points."
Benitez admitted the challenge by Lee Carsley on David Ngog may not have warranted a penalty.
"Maybe it wasn't a penalty but we deserved to score more goals," he said.
"We have had a lot of situations against us this year - and now one for us in a game where we played well and deserved more.
"I was asking David afterwards and he said maybe it wasn't a penalty."
Asked if the international break now came at a good time for Liverpool considering their injury concerns, Benitez added: "I will tell you after the break because every time we lose one or two players. I'm touching wood."
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