Brendan Rodgers is confident of conducting more business before the transfer window closes on September 2, with attacking reinforcements high on the Liverpool manager's shortlist.

The Northern Irishman completed four signings before pre-season, with Iago Aspas, Luis Alberto, Simon Mignolet and Kolo Toure all switching to Anfield ahead of the 2013-14 campaign.

Rodgers is keen to improve his available options even further in the remaining days of the window as the Reds mount a challenge for a return to the Champions League.

"We're always looking to evolve the squad, to improve the group," the boss told local reporters at a press conference in Norway on Tuesday evening.

"We still have some business to do to bring in a few more players. By the end of August I hope that we will have a squad that will be ready to compete and challenge for the top four.

"We need one or two players to cover positions where we're a little bit short, and also probably looking to bring in maybe one or two in the attacking areas. We'll see how that goes.

"The window is still open until the end of this month. We did very well in the early part of the window, when we got four players in - which I'm extremely happy about. If we can add a few more that would be really good for us.

"Our main target is to progress from where we were last season. We finished seventh in the league and we want to move forward.

"The measure will always be Champions League for Liverpool, there's no disguising that. That will always be the case and I believe we have a really good chance of doing that.

"The challenge is very difficult; some of the teams that were already ahead of us have spent massively over the course of the summer again.

"The challenge is still there, it's a very difficult challenge, but we mustn't be frightened of it. We don't see it as a threat, if anything it's an opportunity for us.

"We see this season as a great opportunity to hopefully move forward again. I'm forever an optimist - we will always fight. It's what Liverpool Football Club is about. We never accept second best.

"The challenge is to get into the Champions League positions, but not just be in it, but try to fight and go as high as we possibly can. That has to be the main target, to arrive in the top four."

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Rodgers named a 21-man squad earlier in the day for the Reds' sixth pre-season friendly, against Valerenga on Wednesday - a fixture LFC TV Online subscribers can watch live on this website.

Daniel Agger, Glen Johnson, Martin Skrtel and Luis Suarez remained on Merseyside due to injury.

The boss explained: "Luis picked up an injury. We had an open training session yesterday at Anfield. With him and a number of other players, unfortunately it was just too much of a risk to take them.

"Luis, along with Daniel Agger, Martin Skrtel and Glen Johnson - we just saw this game as too much of a risk for them. So they stayed back to get treatment.

"Daniel Agger, who has been absolutely fantastic over pre-season, took a knock towards the end of the game [against Olympiacos] and had to get some fluid removed from his knee.

"That has just left him a little bit more swelling. We're going to assess that over the next few days and hopeful that he could be [fit] for the weekend.

"Luis, we'll have to wait and see whether he needs a scan on his foot. Glen Johnson, I would think, should be fine - precautionary really, a bit of tightness on his adductor.

"Martin Skrtel just had a problem on the outside of his knee. It was just too much of a risk to take them to this game, but I'm hopeful that most of them should be fit for the weekend.

"All the players have been brilliant over the course of the pre-season, and this is another good game that we're looking forward to. We've been very fortunate - our physical condition has been outstanding.

"The players have worked very hard. This has been the first game where we have had any sort of niggling injuries. To have worked this hard for this long - this is the first time we've had to rest a couple - is a great respect to the players and the medical and sports science team on how hard they have been working.

"It's unfortunate, but we've still got top players here and we'll continue with what has been a very good preparation phase so far."

The journalists gathered at the Reds' hotel in Oslo questioned Rodgers on speculation surrounding the future of Suarez, and the 40-year-old reiterated his viewpoint.

"I'll tell you what I've been saying all summer and what I said most of last season," he said.

"He's an incredible player, Luis Suarez. On the field he is a fighter, he wants to win and he showed that last season.

"We've obviously had a couple of bids from one club that has been nowhere near the valuation. I repeat - nowhere near the valuation of what he is worth in this market. There's no change to that.

"It's the same with any of our players - we're very much a team that's trying to build and go forward. For that, we want to keep our best players.

"We have no intention of selling one of the top players in the world to one of our rivals. The message is very clear: Luis Suarez is very much a Liverpool player.

"There's not even really a discussion point, unless someone comes within anywhere near the valuation of Luis. At this present time, that's not the case."

Although centre-back Agger was not among the travelling party which landed in Norway shortly after 8pm local time, Rodgers responded to a question about the 28-year-old with a glowing appraisal.

The manager added: "He's obviously a world-class defender. Daniel is very committed to Liverpool; he's one of the players that have really impressed me.

"If we're talking about loyalty, he was one of the first players that I spoke to when I became the manager. At the time, there were a number of big clubs looking to sign Daniel.

"But he gave me his word that for as long as I wanted him to be at Liverpool, he would be at Liverpool. He has never swayed from that.

"He has an unswerving commitment to Liverpool which is so refreshing. His loyalty to the club is incredible.

"I would suspect when he signed his new contract last year, he was hoping that this would be the contract that's going to allow him to see out the best part of his career at Liverpool."

Having recorded a 100 per cent record in pre-season to date, Rodgers' charges travel to the Ullevaal Stadium tomorrow to face a side who the coaching staff know plenty about.

"We looked at the team play, I'm sure there will be changes," he said. "The last game they drew 2-2, playing a 4-1-4-1 system.

"The two wingers are reverse wingers that come inside and can cause a problem. The young winger on the left side likes to come in and join in. The left-footed player has technique on the right side.

"The young striker moves well and can finish, with one touch, very well in the box. Norwegian footballers are very honest, work very hard and have quality. We know this is a nice game for us and a good test.

"You produce some wonderful footballers in this country. We know when we come here we're in for a good game. They will work very hard and I'm sure will be very motivated to do well."