Boss Kevin Blackwell will continue to attempt to ease Derek Geary and Jonathan Fortune back to first team action - despite a lack of defensive cover.

The duo are still working their way back to full fitness after lengthy injury problems.

Geary played a full 90 minutes at Watford on Tuesday evening and despite Blackwell's attempts to give Fortune a rest, the central defender was forced into action midway through the first half when Chris Morgan was withdrawn with a rib injury.

Within the space of a few weeks, Blackwell has lost the services of Matt Kilgallon, Kyle Walker, Marcel Seip, Chris Morgan and Andy Taylor - added to the fact that Gary Naysmith is still unavailable for selection.

The United chief said: "We are walking a tight rope with Del and Jon, neither have had a full pre-season.

"Del has had a terrific battle with his knee and done brilliantly to come back, but it is a balancing act, we don't want to push him too far - it's a progressive process and we want to get it right.

"I feel guilty because if they suffer further setbacks they could be career-threatening and I am asking to play when they shouldn't. I want to look after them but sometimes I have had no option"

"The last time we tried to get Jon back he tore a hamstring and was out for another seven weeks but he has done tremendously well, playing three full games in the space of seven days against Bolton, Reading and West Brom."

Blackwell added: "We've brought in Marcel Seip, Nyron Nosworthy and Toni Kallio, and I thought I had it covered until earlier this week when we lost Walker and then Morgan.

"It is difficult to get players in, there seems to be a dearth of quality central defenders - a club like United needs quality central defenders for promotion and it is frustrating because they are all tied up, but we will keep looking."