Birmingham City will be looking to build upon their recent upturn in form when they face Sheffield Wednesday in the Championship on Saturday.

Unbeaten in their last 10 games in all competitions, the Blues could potentially close the gap between them and the play-off places to six points by sealing victory at St Andrew's.

Having held high-flying Brentford to a 1-1 draw last weekend, Birmingham ought to be confident in their ability to see off an Owls side who have lost four of their last six games in the second-tier under the guidance of manager Garry Monk.

Over the years, the Blues have spent a considerable amount of money on players in their quest for success.

Here, using figures from Transfermarkt, we take a look at the six biggest transfer fees that Birmingham have forked out...

Signed from Manchester United in 2010 for a reported fee of £6.3m, Ben Foster featured on 39 occasions for the club before moving to West Bromwich Albion.

During his time at St Andrew's, the goalkeeper helped Birmingham win the League Cup by producing an impressive display in the final against Arsenal.

Brought to the club for a fee thought to be in the region of £6.3m, Nikola Zigic experienced a mixed amount of success for Birmingham.

In 159 appearances, the forward netted 36 goals for the Blues before opting to call time on his career in 2015.

Having impressed during his time at Everton, James McFadden joined Birmingham for £6.75m in 2008 where he struggled to make an impact due to ongoing issues with his fitness.

After scoring 14 goals for the Blues in a four-year stint at St Andrew's, the forward rejoined the Toffees in 2011.

Signed by Birmingham for a reported fee of £7.2m last summer from Dinamo Zagreb, Ivan Sunjic has emerged as a key player for the club during the current campaign.

Having already notched up 33 appearances in all competitions, the midfielder will be determined to lead his side to victory this weekend.

Brought to the club for a fee thought to be in the region of £7.88m from Blackburn Rovers in 2003, David Dunn achieved a relative amount of success during his time at Birmingham.

However, following the Blues' relegation to the Championship, the midfielder opted to move back to Rovers midway through the 2006/07 season.

The biggest ever transfer fee that Birmingham have paid according to Transfermarkt is the £8.39m they spent to lure Emile Heskey away from Liverpool in 2004.

During the two years that the former England international featured for the Blues, he managed to score 16 goals in 78 appearances before moving to Wigan Athletic.