Redknapp's men moved off the bottom of the Premier League thanks to Monday's victory over Aston Villa ahead of their meeting with the leaders at Stamford Bridge.
Charlie Austin's brace at Loftus Road ensured QPR of their second league win this term, a day after Chelsea failed to win in the top-flight for only the second time.
Jose Mourinho's side were held at Old Trafford as Robin van Persie struck in the last minute of stoppage time to salvage a point for Manchester United, cutting Chelsea's lead at the top to four points.
Chelsea bounced back with a hard-fought victory over Shrewsbury Town in the League Cup on Tuesday and Redknapp expects a difficult test when QPR make the short trip across west London.
The former Tottenham boss feels Chelsea are the "best team in the country" but wants QPR to take inspiration from their last visit to Stamford Bridge, which saw Shaun Wright-Phillips score late in a 1-0 win in January last year.
"We pulled off a shock last time, let's hope we can pull off another this weekend," he explained on Thursday.
"We'll need a top performance. They're the best team in the country, the team to beat this season for sure, but we'll give it a go.
"It's a London derby and we're ready for the game. We want to put on a performance for our fans."
Monday's win over Villa was QPR's first in the top flight since August and will provide a much-needed confidence boost as they attempt to inflict a first defeat of the campaign on Chelsea.
Leading Southampton by four points, Mourinho's side have started the season in fine form, although they were given a scare at Shrewsbury - needing Jermaine Grandison's own-goal to progress.
Gary Cahill - one of a host of senior players to feature in midweek - is eager to get back to winning ways in the league.
"I thought we played well against Manchester United but obviously there was disappointment right at the end," he told the club's official website.
"On Saturday it's another home game to look forward to but QPR are coming off the back of a good result. I watched them on Monday [against Aston Villa] and they were great, so yet again it’s another tough game in the Premier League.
"We have to prepare right, rest up after the Shrewsbury game and make sure we're ready."
Mourinho is without suspended defender Cesar Azpilicueta and injured striker Loic Remy (groin) although top scorer Diego Costa and Ramires could return from hamstring and groin problems respectively.
Jordon Mutch, Joey Barton and Nedum Onuoha remain sidelined for QPR with hamstring injuries while Rio Ferdinand serves the first of a three-match ban for comments made on social media.
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