It is understood midfielder Jack is inching towards a summer move to Rangers once his Dons deal expires.
Now Pittodrie boss Derek McInnes has responded by effectively stripping the 25-year-old of the captaincy, instead handing his armband to Shinnie for Saturday’s Hampden showdown with Celtic.
Jack only made his return from a month out with a groin tear during Sunday’s 6-0 romp at Partick Thistle and will most likely start on the bench in any case.
But Shinnie insists his colleague will not let the Reds down if he does make one final appearance.
He said: “I’ve got a great relationship with Jacko. We will both be the same on the pitch. We will be fighting for each other. We’ll be doing everything we can to win.
“We’ve got a great team spirit here and it’s all about the team. That’s how we go about our business.
“Speculation is speculation. We’ve got a cup final here and like I keep banging on about, this is what we’re focused on. This is what we all want to do.
“There’s a Scottish Cup to be won, a winners’ medal to be claimed, so that’s the only thing that matters.”
Shinnie, who skippered Inverness to their cup triumph two year ago, now has the chance to repeat the feat with Aberdeen.
He added: “It’s a big honour but it’s not going to change the way that I play.
“The same can be said of Jacko if we both play.
“We will both do the same things that we have done all season. It’s all about the team. The team is desperate to win this.
“The players, the management and everyone else at this club are just focused on trying to win this game.”