Like many Scots, Conway afforded himself the luxury of supporting an English club growing up and, as an aspiring winger, it was the star power of Ryan Giggs and David Beckham that drew him to United.
Now, at the age of 31 - and six years since he swapped Dundee for Cardiff - he will have the chance to take on the Red Devils.
"I've never played against them before so to end up playing them in the cup, I was delighted personally," the Scotland international told Rovers Player.
"Manchester United were my English team to follow when I was younger. Giggs and Beckham were players I liked, wide players, and I used to watch them...Giggsy was unbelievable to watch.
"But they've been a top team for so many years and to line up against and test myself versus a top team is great.
"When I first came to England that was definitely a thing I'd love to say I'd done, played United and tested myself against the best."
Conway does have experience of taking on another one of English football's most decorated teams during his time at Blackburn, having featured in the quarter-final against Liverpool in April 2015.
Having drawn 0-0 at Anfield, Rovers had a big chance to see off the Reds at Ewood Park but lost to a 70th-minute Philippe Coutinho strike.
"Obviously we went to Anfield and got a draw and when we got them back to Ewood it was an incredible atmosphere," he said.
"It was unbelievable and we were unlucky that night, they probably just had a bit too much for us.
"I'm hoping for more of that against Manchester United. It will be a great atmosphere, especially here at home, and I imagine it will pretty much be a sell-out.
"We're really looking forward to it."