As we all know Celtic are dominating Scottish football. We're fast running out of words to describe how good a season they're currently enjoying in Brendan Rodgers' first term as manager.

Rodgers isn't one to rest on his laurels though and knows better than anyone that continued improvement is the key to consistent success. Stand still for too long and you begin to regress.

We've actually seen this in cycles at Celtic before. Martin O'Neill had a wonderful few years but his side eventually waned without adequate replenishment. The same happened with Gordon Strachan. To an extent that happened under Neil Lennon too, with the team in his final season looking like a shadow of what it was at the start of his reign.

The upcoming transfer window is a big one for the Hoops; they didn't sign in numbers in January and there's undoubtedly work to do to turn the squad into one capable of playing in the UEFA Champions League.

These are the THREE areas of the team that most urgently require investment...

Right wing

With Patrick Roberts set to re-join parent club Manchester City at the end of the season, the depth available to Brendan Rodgers on the wing is fairly dire. Really it's only James Forrest who is a recognised right winger, with the ineffectual Gary Mackay-Steven his backup.

Forrest has improved this season but there are still question marks about his ability to step up a level beyond the Scottish Premiership and a Scott Sinclair type figure on the right hand side could transform the team from Champions League strugglers to contenders for post-Christmas European football.

At domestic level Forrest has a future at the club and is undoubtedly an asset in the Scottish Premiership. But even then it's unfair to rely on him and him alone in a position that is notoriously difficult to be consistent in.

A signing of quality in this area would be much welcomed by supporters.

Central midfield

Nir Bitton has had a strange season with the Hoops and although he's a seasoned international footballer, there's something about him that just doesn't fit with the way Celtic play. Brendan Rodgers' teams are all about quick and dynamic forward passing moves, lung bursting runs, finding space and combinations in the final third; Bitton offers little to any of those aims.

At his best he is a calming presence in what can be a frantic and physical style of match in Scottish football but at his worst he just looks a bit, well, weak.

The back up to his position, Callum McGregor and Liam Henderson haven't exactly made themselves massive hits with the Celtic support either, leaving just Scott Brown and Stuart Armstrong as reliable performers in the position.

Fans do still have hope in Eboue Kouassi, who made his debut off the bench two weeks ago, but another signing in this area is needed to add depth if nothing else.

The right man could compete for a first team place and would ideally be someone accomplished on the ball and someone who has European experience. It's time to take Celtic to the next level.

Central defence

Perhaps the most glaring area of the team that needs improvement, Celtic's defence were pretty much slaughtered in this season's Champions League Group Stages. Conceding a massive 16 goals across 6 matches, only Legia Warsaw conceded more in the groups and they even qualified for the UEFA Europa League knockout stages.

It's clear that while they run the show in domestic football, Celtic need a quality, assured, aggressive and physical centre-back to come in and make the position his own. Sounds easy right?

Of course, finding a man with all those attributes is tough but if they truly have ambitions to make a dent in Europe it must be done. Erik Sviatchenko has been found lacking in big games this season and while Dedryck Boyata's rehabilitation into the team has been a positive, mistakes against St Johnstone and Rangers highlight he may still not be the answer.

This is a position to get sorted Celtic.