The 24-year-old Tottenham winger's future is firmly in the spotlight with Real Madrid keen to attempt a world record deal to take him to the Bernabeu.
Despite not having played for Spurs in almost a month, and while he continues to nurse a foot injury, Bale has reported for duty with Chris Coleman's side ahead of the Cardiff City Stadium clash.
It is understood Bale is concerned about the prospect of risking an injury against the Republic, which could potentially scupper any impending deal.
But Tardelli believes Bale needs to pull on a red shirt on Wednesday, or risk upsetting his Wales colleagues.
When asked if he expected to be facing the winger, Tardelli replied: "I think he will play, he is a Welsh player and he is the best player in the team.
"If he wants the respect of the other players he must play.
"He is a very good player, at the moment he is up there with Cristiano Ronaldo and players of that calibre, and we saw this with what he did for Tottenham last season."
Of the reported £105million fee Real are ready to splash out on Bale, Tardelli added: "Times change but maybe in my time Diego Maradona may have been (worth that much).
"I don't know if Bale is worth that much but if someone pays it that is his value."
But Stoke midfielder Glenn Whelan is not so convinced that Coleman will be able to field his main attacking catalyst, and expects Bale to avoid any risks.
He said: "I am not too sure he will play. He has got a big-money move lined up.
"No one knows if it is on or off but if I was Gareth I would maybe be a little wary of playing before any deal is made.
"But it's up to himself and his manager. I dare say he would like to get a deal done and then play for his country, but if it isn't done, I don't think we'll see him."
While nearly all of the pre-match focus has been on Bale, the Republic have important goals of their own to focus on.
They are firmly in the hunt for World Cup qualification from Group C, and are part of a three-strong group, along with Sweden and Austria, level on points behind leaders Germany.
Next month sees Giovanni Trapattoni's team face the Swedes and Austrians in two games which could define their campaign.
And Whelan knows it is vital to continue a good run of form which has seen them lose just once in 2013, to World and European champions Spain.
He said: "It is massive for us, we have gone on a good run and we need to keep that confidence going as we have got two big games next month.
"We put in a good performance against Spain, even though we lost, and everyone knows how friendlies can help build confidence, so we want a good result on Wednesday.
"We have a few new players around the squad but they want to prove they can do a job on the big stage and we want to go into those games next month on a good performance and with the right result.
"This is a derby game and we know it will be tough."