Wigan are playing their first cup semi-final since facing Arsenal in the 2006 League Cup, where they won on the away goals rule following a 2-2 aggregate draw to play Manchester United in the final, where they were beaten 4-0.
However, the Latics are again battling to stave off relegation from the Premier League and are currently in the bottom three, level on points with Sunderland but with a worse goal difference.
With the Premier League set to receive a financial boost thanks to the new £3billion television deal for next season, Whelan knows remaining in the top flight is crucial.
"Staying up is more important than winning the semi-final," Whelan told the Evening Standard. "No question about that. I have promised the players a holiday in Barbados not for winning the FA Cup but for staying up."
Whelan famously broke his leg when playing for Blackburn in the 1960 FA Cup final against Wolves and is set to lead the team out onto the Wembley pitch at the weekend.
But the 76-year-old has witnessed a decline in the tournament's importance due to the ever increasing Premier League revenue which has placed that competition at the forefront of clubs' minds.
"You wouldn't imagine a change like that could happen. When I was growing up and playing, winning the FA Cup was something absolutely unbelievable," Whelan said.
"It (the decline) has happened. You get so much money out of the Premier League, it's just phenomenal. And what these clubs are going to get next season is unbelievable.
"It makes this season's relegation battle all the more desperate."
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- Premier League