Sheffield United boss Kevin Blackwell again has defensive problems to contend with ahead of Saturday's clash with Derby at Bramall Lane.

The loss of Chris Morgan to a torn rib muscle is the latest in a long list of injury setbacks to hinder Blackwell's promotion plans this season.

Possible replacements Marcel Seip and Andrew Taylor are both sidelined with hamstring problems, while Gary Naysmith remains absent due to his long-term knee injury.

But Blackwell can recall Toni Kallio to his side following his return to Bramall Lane on loan from Fulham.

The Finland international was not eligible for the Watford game due to delays in his paperwork.

Recent signing Nyron Nosworthy is expected to continue at the heart of defence after making his debut at Vicarage Road, with Jonathan Fortune likely to partner him.

Michael Tonge will make his Derby debut against his former club.

Tonge, a Blades player for eight years before signing for Stoke in 2008, has joined Derby on loan from the Potteries club for the remainder of the season.

He could replace Lee Johnson in the centre of midfield after the diminutive playmaker returned to Bristol City following the conclusion of his loan.

Another deadline-day recruit - Manchester City defender Javan Vidal - is expected to be included in the squad after arriving on a loan deal until the end of the campaign.

A further change to Nigel Clough's squad is the departure of DJ Campbell. Last weekend's victory over rivals Nottingham Forest was the final game of his loan spell and the Leicester striker has since joined Blackpool on loan.

Defender Dean Leacock (knee) and midfielders Lee Croft and Lee Hendrie (both hamstring) are expected to remain sidelined.