Italian Di Canio, who enjoyed a great relationship with Redknapp at West Ham United between 1999 and 2001, could deliver a huge blow to his old boss's chances of keeping QPR up if he can inspire Sunderland to a surprise win at Chelsea and Rangers lose at home to Wigan Athletic.
"I know Harry looks back fondly at his time with Paolo. They still speak and share a love of football," Redknapp's son Jamie, the former Liverpool midfielder, wrote in a lively Daily Mail article describing some of Di Canio's antics.
Flamboyant Di Canio often made headlines as a player at West Ham and elsewhere and his appointment has stirred controversy because of his "I am a fascist" remark he made eight years ago.
On Wednesday he rowed back from that stance saying: "I do not support the ideology of fascism. I respect everyone. I am a football man. This and my family are my focus."
Di Canio will take charge of his first game as a Premier League manager on Sunday hoping to galvanise a side who have slipped into the relegation battle.
The fear of demotion to the Championship (second division) is still a threat to the bottom nine clubs from Southampton in 12th place on 34 points down through Stoke City (34), Norwich City (34), Newcastle United (33), Sunderland (31), Wigan (30), Aston Villa (30), QPR (23) and Reading (23).
QPR host perennial relegation escapologists Wigan on Sunday while Di Canio will try and inspire a major upset against fourth-placed Chelsea by ending Sunderland's run of eight matches without a win -- a statistic that cost Martin O'Neill his job.
They have shocked Chelsea before in the recent past, winning 3-0 there in Nov. 2010, and while a win is unlikely Chelsea could be tiring with so many games piling on top of one another.
Aston Villa, who have been in the top flight since 1988 and are also deep in the mire, cannot afford another slip up at Stoke, who themselves are not clear of danger.
With champions-elect Manchester United not playing the outgoing champions Manchester City until Monday evening (1900GMT), attention will also focus on the continuing race for the Champions League places.
Third-placed Tottenham Hotspur, who like Chelsea and Newcastle United are involved in Europa League action on Thursday, host Everton on Sunday, while Arsenal, who are fifth, are at West Bromwich Albion on Saturday.
United and City have a few days of extended rest before they meet at Old Trafford.
Almost a year ago City beat United 1-0 to take a huge stride towards the title but the red half of Manchester enjoy a 15-point lead with eight matches to play and are cruising towards a 20th English league crown.