Mamadou Sakho
Sakho still looking for full fitness. (Reuters)

Liverpool defender Mamadou Sakho has admitted he is still looking to discover his full fitness levels following his move to Anfield.

The France international was one of three deadline day signings in August along with fellow defender Tiago Ilori brought into to help fill the void left by Jamie Carragher who retired at the end of last season.

The 22-year-old has started every game for Brendan Rodgers' side since his move from Paris, helping Liverpool maintain their lofty status near the summit of the Premier League.

But having been substituted after an hour in his last two Premier League outings, Sakho admits he is still looking to improve his fitness levels as he comes to terms with the change in styles between Liverpool and the Ligue 1 champions.

"I'm not yet at 100 per cent, I'm progressing with each match that we have," Sakho said, speaking to Liverpool's official website.

"I work every day at training sessions to progress and to achieve the highest level. It's logical that I would improve.

"When you arrive in a country you don't know, you have to learn quickly about the differences in the game and have to get on and adapt yourself to the qualities of your team-mates."

With Martin Skrtel, Kolo Toure and Daniel Agger also vying for a starting berth Rodgers has a wealth of options at centre half. However, after seeing his side concede four of their last six goals from set pieces, the Liverpool boss has warned his players they must rectify this weakness in order to maintain their push for Champions League football.

"It's something that we need to address, for sure," Rodgers told the Liverpool Echo after witnessing Paul Dummett turn in a Yohan Cabaye delivery during his side's 2-2 draw with Newcastle United.

"We have to be more aggressive and more switched on. It's concentration.

"The goal at home to Crystal Palace was disappointing. That was a poor goal to give away, but thankfully it never cost us.

"Here, conceding from a set piece put us on the back foot. We were looking forward to the second half at 1-1, and suddenly we were behind.

"It's something for us to work on, but in football there is always something to improve on. At this moment, that is an area for us to look at."