The London side are just five points above the League One relegation zone, so a trip to the league leaders is not the ideal follow-up.
But Donachie insists his side will be up for the fight when they make the long trip up to North Lincolnshire.
"We have just got to work hard now, get on with it and put things right on Saturday," he declared.
"Nobody was up to par in midweek, so there is no point feeling sorry for ourselves."
Donachie is trying to add new faces to his squad, though fresh faces at the New Den may have to wait until next week.
One player Donachie will not be able to call on this weekend is striker Darren Byfield, who serves a one-match ban having received his fifth booking of the season last Saturday.
Winger Alan Dunne must also sit out the game through suspension, having been shown a straight red card in midweek - meaning he will serve a three-match ban.