When Wayne Rooney was appointed as Derby County manager on a permanent basis in January, the club were facing the real prospect of relegation to the third tier of English football.

However, since taking the reins at Pride Park, the 35-year-old has inspired his side to an impressive run of form which has allowed them to move nine points clear of the Championship drop zone.

Having secured a point in their clash with arch-rivals Nottingham Forest last Friday thanks to a late goal from Colin Kazim-Richards, Derby will be aiming to get back to winning ways tomorrow when they face Cardiff City.

However, the Rams may be forced to make the trip to Wales without the presence of first-choice goalkeeper David Marshall.

The 35-year-old was replaced by Kelle Roos midway through Derby's clash with Forest after suffering a back injury.

Speaking to the Derby Telegraph about Marshall's injury following his side's 1-1 draw, Rooney said: "Not sure yet, we will assess him tomorrow (Saturday).

"I think it is a problem with his back, hopefully he is okay."

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Although it is fair to say that Marshall was at fault for Forest's goal last Friday, it would be somewhat of a blow for Derby if he is ruled out of their upcoming clash with Cardiff.

A mainstay in the Rams' starting eleven this season, the Scotland international has overtaken Roos in the club's pecking order since joining the club last summer.

With eight league clean-sheets under his belt in the Championship already this season, Marshall will be determined to reach double digits when he returns to full fitness.

If Marshall is unavailable for Tuesday's game, it will be intriguing to see whether Roos is able to step up to the plate.

Despite achieving WhoScored ratings of 6.95 and 7.16 in Derby's recent victories over AFC Bournemouth and Queens Park Rangers, the 28-year-old has struggled for consistency during his time at the club.

Limited to just five league appearances during the 2020/21 campaign, it may turn out to be Roos' last chance to impress Rooney ahead of the summer transfer window.