Celtic remain unbeaten domestically this season as they look to take another step towards completing the final leg of a treble when they take on Rangers at Hampden on Sunday.
Brendan Rodgers' side thrashed Rangers 5-1 in their first league meeting this season as they raced away from their Old Firm rivals for a sixth successive title win.
"If you are a betting man you would be daft to bet against Celtic", the former Parkhead striker turned pundit told Press Association Sport.
The pundit has told The Scottish Sun that Celtic can put out the reserves against Rangers next week, and predicted that even if Caixinha "gets Rangers going", they will still only finish third - the position they now hold in the Scottish Premiership - next season.
Alex McLeish says he was never close to a return as Rangers manager before the eventual appointment of Pedro Caixinha.
JOHN HARTSON reckons Rangers won't do better than a third-place finish NEXT season.
"I think they will have too much and they have a big chance to get to a final".
"I think over the last few weeks even when we havent played well we have managed to get the win and we have also played well and got results".More news: Juventus coach Max Allegri happy to reach Coppa final despite defeat
McLeish, who was Ibrox boss between 2001 and 2006, was invited by the board to discuss the position vacated by Mark Warburton in February.
He said: "The league game coming up between Rangers and Celtic is a nothing game now".
"I was never 100%, "yes, I am going back to Rangers".
"We saw in the last Scottish Cup semi-final when Rangers beat Celtic".
"Then in the games after that it was going to be cricket scores and I think we shut up a few of the critics with a couple of performances".
"It is not to say that on their day, as they proved at Celtic Park, they aren't capable".
"We are thinking about having one more trophy for the club, I'm not thinking about the opponent", he told Rangers TV.
"I am not saying they need to be at that level in terms of organisation, pressing and discipline, but that's what they need to get back to".