The Tottenham winger is in a stunning vein of form, and broke Scottish hearts with a late double which gave Wales a 2-1 win when the sides met in Cardiff in October.
The 23-year-old suffered an ankle knock in Tottenham's 1-0 defeat against Fulham on Sunday, and has not yet trained this week after linking up with Chris Coleman's squad.
But there are no doubts over Bale's availability for the 'Battle of Britain' clash, and striker Sam Vokes believes the Spurs star's presence will be a big boost.
He said: "We think he is going to be fit, he is in and around the team and will be training in the next couple of days with Friday in mind.
"It is fantastic to play alongside him, the last couple of goals I have scored for Wales have come from his assists, and in the Scotland game here he turned the game on its head.
"He has been different class for club and country for a while now, every game he plays in he is excellent and he will be a big player for us on Friday."
For the first time in Coleman's reign, Wales head into a round of fixtures with some momentum behind them in Group A.
The Dragons have won two of their last three games, against Scotland and Austria, and are keen to continue their progress in Glasgow.
Burnley striker Vokes knows prevailing in the hostile Hampden cauldron will be a sure-fire indicator that Wales are again heading in the right direction.
"It would be a huge step forward, we can take confidence from our recent results against some strong opposition," he said.
"It will be a different sort of game on Friday as you will have the occasion of it being a derby, but hopefully we can take confidence into the game.
"It is a 'Battle of Britain' which adds to the passion and pride that goes with it. There was a great atmosphere here in Cardiff and it will be the same again this time."
This weekend's eagerly-awaited clash will also mark Gordon Strachan's first competitive fixture in charge of Scotland, with Craig Levein having made way shortly after Bale's last-gasp heroics in the reverse fixture.
And Vokes is wary of the reaction the presence of a new man in charge could have on the hosts.
"We have gone through a manager change recently and it is one they will look for a good reaction from, but we need to focus on our own game and go from there," he said.
Vokes found the net in the 2-1 win over Austria last time out, becoming the first player other than Bale to score for Wales under Coleman.
With Steve Morison again an injury absentee, Vokes may have the chance to stake a claim for the number nine shirt, but will wait to see which system Coleman operates, with Craig Bellamy and Bale also options for the central role.
"Steve has made a lot of his chance in the number nine slot, and it has been up to me to make an impact off the bench," he said.
"Hopefully Friday is a big chance for me, although Craig Bellamy started there against Austria so it depends which way the manager wants to go, but I want to put my name forward."