A draw or better will see United go top ahead of City's New Year's Day trip to Sunderland.
United will be firm favourites to give long-serving manager Sir Alex Ferguson a 70th birthday present of a victory against a Blackburn side that has won just twice in the league so far this season.
But while beating Rovers would be no surprise, ending the calendar year on top of the table would be a boost to a United team beaten 6-1 in the league by City, knocked out of the League Cup by second tier Crystal Palace and no longer involved in the Champions League following a shock loss to Basel.
"You are going to get setbacks," long-serving winger Ryan Giggs told www.manutd.com. "It's about how you react to them.
"Thankfully we've come back strong.
"They can help in a way. I've experienced that throughout my career - you might hit bad form or miss a good chance, and you can't wait for the next game so you can rectify it.
"I'm sure all the lads felt like that after the City game and after Basel, which was a big disappointment too."
Many had predicted Blackburn boss Steve Kean would have been out of a job by now but Venky's, the Indian-based poultry firm that owns Rovers, are standing by the Scot.
And Kean himself revealed he'd had words of support from compatriot Ferguson among a host of consoling words from fellow Premier League managers.
"We had a good chat," said Kean.
"For him to take the time out to phone me with a message of support shows the stature of the man. I was really impressed by that.
"What he said was very encouraging. When you are getting managers like Sir Alex, Harry Redknapp, David Moyes and Alan Pardew saying hang in there, you are doing the right things, wait until you get your lads out of the treatment room and you will be fine, it gives you confidence.
"They have been in the game a long time and been in similar situations. I listen and take their advice because they have been round the block."
Source: AFP
Source: AFP