Victory this time would allow Rangers to move to within one game of retaining the championship at the same venue they claimed the crown almost 12 months ago on the final day of the campaign.
"It will be a difficult game because Dundee United are now on form and they are a great team," Papac said.
"But we have shown this season we can play well against them and I believe we can be good against them again in this game.
"There are six games to go and the finish to the season is very important for us. We need two games to win the championship."
Papac added: "It's totally different this year. Last season we tried to catch Celtic all season and we played until the last game not knowing who would win the league.
"This season is different because we have a good gap and 13 points is great.
"But, if you play for Rangers, you have to give your best in every game."