And boss Nigel Clough believes they could be the key the reaching round three and a possible dream tie with a Premier League giant.
“Our following is going to be absolutely key with the wonderful amount of tickets we've sold,” said Clough.
“It's a break from the league and we're looking forward to it.
“It gives us all a boost. To sell out is brilliant. That's why it was such a good draw next to being at home, it is one of the closest we could have got and that shows from the amount of fans we're taking, which is great for them.
“I hope it's a bit warmer than it was at Crawley and it's certainly much closer for everybody to get to.
“I think for lower league clubs the second round is very exciting because of what it can bring.
“To get a draw against a higher club after the win at Sunderland, let's go and have a go.”
Although Doncaster are struggling and in the drop zone and Stags have won six of their last seven, Clough insisted the Yorkshire club will still be favourites.
“We are still underdogs as they are still a better team and in the league above,” he said.
“They will see it as an opportunity as well to first of all get into the third round and it can be a springboard for your league form as well. We found that over the years, certainly at Sheffield United, with cup runs.
“We were struggling in the league and all of a sudden had a good cup run and took that into our league form as well.
“They are much better at home than they are away from home. If you look at their record they have struggled away from home.
“On their own patch they're not too bad and we are still playing a team from the league above with better players.”
He added: “What has shown up in the three wins at Sunderland, Stevenage and Crawley is that you're going to need a break.
“In all of those games they hit the woodwork against us.
“You need a little break, especially when you're playing better teams and we will need that on Saturday.
“We need a little bit of luck, a good performance and we have got to try to get a goal like we always do. But when you've got someone like Rhys Oates in the line-up you're more likely to get one.”
Should Stags get through, Clough believes it's high time they got a home cup draw.
“We want one of the big clubs at our place if possible. We've had a lot of away draws.
“We are due a home draw if we can get through or if we can get a replay and get them back to out place, that would be brilliant as well.”
Stags; win at Crawley last weekend and a blank week to follow have been huge boosts for Clough and his men ahead of the FA Cup.
“It was an important win last Saturday as we certainly didn't want to lose back-to-backs over the two away games,” said Clough.
“It was a tough week with three games in a week and a lot of travelling.
“But we are going for wins. We set up to get the win - not being defensive and then maybe trying to nick a point away from home.
“We are trying to win every game. To win two out of the three is better than staying unbeaten and winning one and drawing two.
“Having a blank week this week is very important after the week we've had with all the travelling and the three hard games.
“If we'd still been in the Papa John's this week and had to put a team out it would have been more of a problem.
“We're pleased for a clear week building up to an important cup game and six points at stake with two home games to follow.”