Liverpool rocked by Martin Kelly injury but relieved over Daniel Agger

Martin Kelly: The right-back will miss most of the season with a serious knee injury (Getty Images)

Liverpool defender Martin Kelly has been ruled out for "a significant period of time" after rupturing his anterior cruciate ligament in the defeat to Manchester United on Sunday. The 22-year-old limped off late in the 2-1 defeat after falling awkwardly and appearing to twist his right leg.

The right-back has had the injury assessed and it requires surgery, which is likely to rule him out for at least six months. "Martin Kelly is likely to be out of action for a significant period of time after scans revealed he suffered an ACL rupture of his right knee during the match against Manchester United on Sunday," said a statement from Liverpool. "The England international will now require ACL reconstruction."

There is slightly better news for Brendan Rodgers concerning his other two injury worries, however.Centre-back Daniel Agger was carried off in the second half after a collision with team-mate Glen Johnson. Considering the Dane's injury record there was immediate concern but initial examinations have revealed there is no ligament damage, only what the club describe as "a significant bone bruise to the left knee".

"No ligament damage was sustained but further tests will be carried out before it can be established when he will be able to return to training," Liverpool said.

Forward Fabio Borini was forced off at half-time at Anfield with a bruised foot and swollen right ankle and although there is no fracture he requires further investigation at the club's Melwood training ground.

Rodgers has urged his players to be more positive in front of goal in order to fully reap the benefits of their new style. Since succeeding Kenny Dalglish in the summer the Northern Irishman has been working on getting his squad adapted to a game-plan based around lots of possession.

In probably their best display so far Liverpool dominated Sunday's game, even after Jonjo Shelvey was sent off before half-time, but ended up losing having not taken advantage of their control.

Rodgers wants his players to threaten the goal more, especially as they have scored only four times in five Premier League matches, but is happy with the way everything else is developing. "I said to them at half-time we have to be effective as well," said Rodgers, who is currently working to bring in a goalscorer to fit into his system in January.