QPR are two points adrift of safety with just five matches remaining and return to action for the first time since suffering an agonising 1-0 loss to leaders Chelsea on April 12.
That match was settled by Cesc Fabregas' 88th-minute strike, which was Chelsea's first shot on target, after a valiant showing from QPR.
"I'm fully expecting a blood and thunder London derby. We will be positive and on the front foot and going for the win," he said.
"We've conceded a lot of late goals this season and we're not happy about that. We really do need to stop conceding those late goals and keep concentrating right to the end.
"I'm not sure [what is needed to avoid relegation], if you win three games you are obviously going to stay up but I'm not sure. As long as we're above the line come the end of May, I'll be happy."
QPR, who lost 2-0 in October's corresponding fixture, could welcome Leroy Fer back from a two-month lay-off with a knee injury, but Rio Ferdinand (knock) remains on the sidelines with Eduardo Vargas (knee).
Allardyce is aware that QPR are fighting for their lives at the bottom of the table, but demanded his players match their commitment.
"We've made life far too difficult for ourselves, but we have to continue to make sure we do better than we are at the moment," he said.
"We've got QPR and Burnley next who are fighting for their lives. We have to match that fight.
"The focus has to be that we have to try and finish the season on a high."
