Saints shot down their east midlands rivals thanks to a late Tom Wood try that earned a 21-20 success in the Aviva Premiership play-off semi-final at Franklin’s Gardens.
That victory sets up a mouthwatering clash with Saracens in the May 31 Twickenham showpiece.
But first, Saints must travel to Cardiff Arms Park to take on Bath in the Amlin Challenge Cup final on Friday night.
And when asked how significant the Tigers triumph could be ahead of two massive weeks for his club, Mallinder said: “It’s significant in terms of turning Leicester over.
“We’ve had some great tussles with them over the years and Friday wasn’t without controversy.
“It was a real good advert for the game and okay we did get a few yellow cards and a red card, but it was a proper game of rugby.
“Hopefully that’s going to give us momentum.
“We’ve got two finals in two weeks to look forward to.
“We’ve already been in an LV= Cup final and didn’t manage to win that one, but we’ve got two chances to bring some silverware back to the people of Northampton.”
And Mallinder is adamant that his team have achieved nothing yet, urging them to end their 14-year wait for a major trophy by beating Saracens.
“We’ve beaten Leicester, which is good, we’ve won the semi-final and got through to the final,” he said.
“A significant moment will be when we win the final of a big competition.
“We were in the final of the Heineken Cup (in 2011), we were in the final of the Premiership last season, so a significant moment will be when we win a big one.”