Palace welcome the champions to Selhurst Park in a rich vein of form, having produced a confident display to beat Arsenal last time out.
But Craig Shakespeare's side are set to arrive in south London in good spirits after a spirited performance against Atletico Madrid in the Champions League quarter-finals in midweek.
The Eagles are six points clear of the relegation zone and Allardyce is adamant his players cannot afford to take their foot off the gas as the finish line approaches.
"We have given ourselves a little cushion above the bottom three. We have won five out of six but I have told my players not to lose focus,” Allardyce insisted.
"It'll be an interesting challenge for us to see if we can take on Leicester, master their tactics and be clever enough to beat them.
"You'd expect one or two changes for them, but they've got a very good squad. They'll be tough to beat, back to their old selves.
"Tactically Leicester were brilliant on Wednesday night. Atletico rarely had a shot on target. That's the size of the task we've got.
"We hit the mark against Arsenal. We've got to look at the Leicester game and say 'can we make it 4 [in a row at home]?'"
Patrick van Aanholt is in line to return from injury but the game is set to come too soon for striker Loic Remy.