Arguably the biggest positive about Liverpool this season has been their defence.The Reds entered last season conceding goals like they were going out of fashion, but the following year has seen them transformed into a sound defensive unit.Virgil van Dijk is indisputedly the best defender in the Premier League, Joe Gomez has come on leaps and bounds this season and Alisson Becker has a remarkable 16 clean sheets already.However, special praise has to be reserved for the club's full-backs: Andrew Robertson and Trent Alexander-Arnold.Rewind just two years and Robertson was quietly going about his business at Hull City, while Alexander-Arnold was trying to make his name in the Liverpool academy.

Liverpool's brilliant full-backs

It's an unlikely duo, but they've quickly established themselves as some of the finest wide defenders in Europe and just in case you disagree, their statistics speak for themselves.

Even if we ignore the pile of clean sheets they've amassed, we can find plenty of quality in the offensive aspects of their game.

No defender has produced more assists than Robertson in the Premier League this season and Alexander-Arnold is just behind him with a total of six.

Liverpool tweet all their assists

In terms of the latter, he hit the headlines this week after providing a hat-trick of assists against Watford, becoming the youngest player in the competition's history to do so.

And ahead of the Merseyside Derby, it's clear that Liverpool want to celebrate their brilliant full-backs and have uploaded a video documenting all their assists this season.

The compilation - titled the 'assists challenge' - has already amassed over 4,000 'likes' less than hour after its publication. The full video can be seen down below: 

A nightmare for the opposition.

The sheer range of assists from corners, penetrating crosses and incisive through -alls show that Liverpool have incredible creative influences on both wings.

Klopp has struck a clear balance between his two full-backs maintaining defensive solitary and also causing havoc in the final third, resulting in 16 assists in total.

If Liverpool are to maintain their trajectory to the Premier League title, they will need their dynamic duo to keep providing ammunition into the penalty area. 

It's been argued that a key weakness in the Liverpool team is their lack of a Philippe Coutinho-like player but Robertson and Alexander-Arnold have been able to create chances in their own ways.

As the video proclaims, the assists challenge is 'to be continued' and it will be intriguing to see which full-back finishes the season with the greater tally.

At the end of the day, though, the number of Premier League trophies is the statistic they'll really care about.

Who do you think will produce more assists - Robertson or Alexander-Arnold? Have your say in the comments section below.