Paul Merson: Liverpool can win title if they sign Southampton star Virgil van Dijk in January

Arsenal legend Paul Merson says Liverpool can win the title if they complete the signing of Southampton star Virgil van Dijk in January. The centre-back moved to St Mary's Stadium from Celtic in 2015 and has been a key player in the heart of their back four.

The Netherlands international has started in all Premier League and Europa League games this season and has excelled under Claude Puel. His form for Southampton has seen him attract interest from other Premier League clubs.

According to Goal.com, Van Dijk is a transfer target for the Merseyside club and their arch rivals Manchester United in the mid-season window. Merson believes the Reds can improve their back four, despite their impressive form this season.

Liverpool are second in the table with 30 points from 13 games. Merson claims the centre-back is valued around £50m ($62.4m) and claims Jurgen Klopp's side will go on to win the title if they manage to secure Van Dijk's signature.

"For me, I think if Liverpool get together and go and buy Van Dijk for £50 million in January, they will take some beating," Merson told talkSPORT.

"They've got the firepower going forward, I just don't think they've got it at the back. I know they've done it this season so far, but defensively they aren't going to be good enough [against the big teams].

"But if they can go out and get Van Dijk, I think £50 million, that nearly wins you the Premier League."

Meanwhile, Puel has pinpointed the areas in which Van Dijk has improved his game under his guidance. The Southampton manager has backed the centre-half to become one of the best defenders in the world.

"I think Virgil, since the beginning of the season has made progress. Virgil has improved both technically and tactically as well, in the duel he is fantastic," Puel explained, as quoted by the Daily Mail.

"For me, he has all of the qualities to become one of the best defenders in the world, there is no problem for this, Virgil has the answer - he must continue his work to continue his progress.'

"It has been a new thing for him this season to defend with 50 or 60 metres behind him, and it is difficult to leave that space.

"For me, it is important to defend at a high level, especially when we play against a great team with strikers who are very fast, it is important to be able to anticipate all of the possibilities of the opponent."