Whites captain Cooper has not featured since injuring his hamstring in the early stages of December's clash at home to Brentford but the centre-back says he has been back on the grass for the last two weeks and is gearing up towards a return.
The skipper has also made an honest admission about his side's display in last weekend's 3-0 defeat at Everton but says the full focus is on providing the right reaction in today's Roses derby at Elland Road.
Writing in the matchday programme, Cooper said: "Missing games over recent times has been difficult, because naturally all I want to be able to do is get out on the pitch and try to help, especially when things haven't been going our way.
"I'm now in the closing stages of my recovery so it's been good to get back out on the grass as Thorp Arch over the last couple of weeks.
"I now can't wait to be fully fit and get back involved again."
Reflecting on last weekend's loss at Goodison Park and today's clash against the Red Devils, Cooper said: "Last weekend at Everton, we weren't at the races.
"Everyone knows it wasn't good enough and we didn't reach the performance levels we know we are capable of.
"Today's game against Manchester United needs no introduction and everyone is determined to show a reaction.
"We know the atmosphere is going to be electric and you're going to be supporting us all the way."