Stuart McCall's side will travel to Pittodrie in the knowledge that victory would secure second place in the table as well as an additional £240,000 in prize money. There is also the added benefit that Motherwell would begin their Europa League campaign on July 17 rather than in the first round of qualifying ties, which are held on July 3.
Form suggests there should be little between the sides, with Aberdeen having won 3-1 at Fir Park at the start of the season, Motherwell having triumphed by the only goal away from home on Boxing Day and the third meeting between the sides ending in a 2-2 draw.
However, McManus recalls his arrival at the club last summer when McCall was piecing a squad together on a restrictive budget after losing six senior players and the defender insists no-one could have given the team the slightest chance of having second place within their grasp on the final day of the campaign.
"We are not under pressure because I don't think anyone expected us to be anywhere near this," said McManus. "Aberdeen should be miles ahead of us with the way it's went and we are just delighted to take it to the last day. We don't want to be nervous about it because we have qualified for Europe and blown away our expectations from the start of the season.
"It is not quite the same as a title being decided on the final day or something like that. I might be wrong but I don't think anyone mentioned us being second or third in their predictions and rightly so. It is a massive overhaul when you are losing five or six players from your first team. Everyone was talking about how great the players who had left were.
"You hear people talking all the time about the budgets of clubs up here in Scotland. When you come in from the outside, though, you see how incredible it is. It is incredible for a club like this to be going for second place."
Had McManus taken a different path after leaving Middlesbrough on a free transfer 12 months ago, he could have been facing an altogether more unpleasant kind of drama this weekend.
He spent time training with Hibernian before opting to move to Fir Park and has had no cause to regret his decision given the fact the Easter Road side must defeat Kilmarnock at home tomorrow to avoid the relegation play-off place.
"I had possibilities with five or six clubs. It wasn't just Motherwell and Hibs," said McManus. "It was the first time I had ever been in that situation in my career and I felt I should be honest and up front. I spoke to the majority of the managers.
"I have always gone with my gut feeling and did the same then. Coming here has been one of the best things I have done."
McManus is out of contract this summer but considers it more than likely that he will agree a longer stay at Motherwell and be part of the club's sixth venture in European football in the past seven seasons. "I would be very surprised if I am not here next year," said the 31-year-old. "When you are my age and you are coming up to play in Scotland, you are not haggling over a few quid because there isn't much to haggle over.
"I have loved it here, though. I never expected it to go as well as it has but you get a feeling about places and I felt it on the very first day I came in here."
Naturally, there is prestige attached to taking Motherwell to second in the table for a second successive season, but there is an added incentive for the squad since that would also earn them an extra fortnight on the beach.
"It would be quite nice," said McManus with a smile. "When you have played a full season, the one thing you look forward to is your holidays."