Despite an upturn in form of late, Reading are still among the favourites to be relegated to the npower Championship after just one season in the top flight.
Midfielder Leigertwood fondly remembers his cup run with the then-Championship side two years ago, when the Royals beat Everton and West Brom before exiting the competition with a 1-0 quarter-final defeat to eventual winners Manchester City.
Reading's cup run that year coincided with a nine-match winning streak that eventually took them to the npower Championship play-off final, and Leigertwood hopes the Royals can enjoy a similar bounce this season as they look to preserve their top flight status.
"The FA Cup run that year was good for us. It definitely helped our league form at the time and hopefully we can put a good run together this season," Leigertwood told a press conference.
"We beat some good teams - Everton, West Brom and we had a tough game at Stevenage. We went out against Manchester City and we gave a good account of ourselves there. It definitely helped our league form."
On paper Reading should have no trouble swatting aside Leigertwood's former employers Sheffield United in the fourth round.
Leigertwood regards the South Yorkshire club, who have won the FA Cup four times, as something of a sleeping giant.
"They are a big club, definitely," Leigertwood said. "They are very passionate up there about their football. You are either a red or a blue."
He added: "It will be a tough game on Saturday. They haven't been doing as well in their league of late but all form goes out of the window in FA Cup games so it should be an exciting game."