Some of the Wigan public will share that conviction this afternoon when third-placed Ipswich, one of their team's main rivals for automatic promotion, visit the JJB Stadium. The 25,000-capacity ground will be more than half full for the Championship's match of the day.
That has not always been the case this season. When Rotherham visited in October fewer than 8,000 people turned up, yet Whelan, a self-made multi-millionaire and a former Blackburn Rovers player, is convinced the club will be turning fans away next season should, as he suspects, they join English football's elite.
Wigan Athletic's startling rise through the lower divisions is a real rags-to-riches story. It is exactly 10 years since Whelan bought the ailing old Third Division club. A crowd of only 1,884 watched the first game under his leadership at the run-down Springfield Park, now a housing estate on the edge of town.
Back then Wigan were in the bottom division, selling players to survive and struggling to pay the milk bill. Whelan's arrival was virtually ignored outside the town, yet locals now liken it to Roman Abramovich taking over at Chelsea. After all, the new owner, who is now joint 155th in Britain's rich list with an estimated worth of £290m, had already progressed from selling toiletries on Wigan market to spearheading the JJB Sports empire.
Now Whelan, 67, stands on the brink of something very special after investing around £50m in his beloved club. Bruce Rioch and Steve Bruce are among those to have managed the club in Wigan's blossoming decade but Whelan says his best business transaction was bringing Paul Jewell to the club.
The former Bradford City and Sheffield Wednesday manager, who played for Wigan before that, is three months short of celebrating his fourth anniversary in charge. Yet he believes Wigan, elected to the Football League in 1978, would now be playing at the same level as the Conference North leaders Southport, the club they replaced 27 seasons ago, but for Whelan.
"Without his backing the club would certainly still be at Springfield Park," said Jewell. "Wigan Athletic have made dramatic strides under his leadership and are still moving forward. I don't think he'll rest until he sees Wigan in the Premiership."
For years Wigan fans have been forced to live in the shadows of the town's famous rugby league club but the tide is beginning to turn. "We're not pretending to be the most fashionable club in the world, but we are trying to make it more attractive for players to come and play for us," added Jewell, who has attempted to play down the significance of this afternoon's fixture.
"People are labelling the Ipswich game as a promotion decider," he added. "It's not. Even if we win, we have another 10 hurdles to clear before the end of the season."