The Catalan giants agreed a €40 million deal for Valencia and Spain striker David Villa on Tuesday, with speculation rife that the Gunners' skipper Fabregas is next on Pep Guardiola's hit-list.
Reports on Tuesday claimed that Fabregas had informed Wenger of his desire to return to Nou Camp after 10 years at Arsenal.
And Redknapp revealed in his column in The Sun that he expects Fabregas to leave the Gunners for the "best club in the world" this summer.
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"I will be absolutely amazed if the lad doesn't join Barcelona. Let's face it, he's a Spanish lad, he grew up in the same youth team as half those established stars, his family is there and so are his mates," he said.
"And that's before we even get to the fact he'll be joining the best club in the world - because after signing David Villa too, that's how I rate them - with the chance of the biggest honours in club football every year.
"I know Arsenal aren't exactly small fry but this is Barcelona we're talking about, where major trophies are expected every year - and usually not too far from arriving either.
"Which player in the world wouldn't like to be lining up alongside superstars like Lionel Messi, Xavi and Andres Iniesta? I can't think of too many. None of which will be any comfort to Arsenal supporters, I know, because Cesc Fabregas is one of those special players who would improve any team he was in."
Gunners' fans will no doubt consider the loss of Fabregas as a massive blow to their hopes of ending a trophy drought that dates back to the 2005 FA Cup.
But Redknapp believes they will cope without the Spaniard and that Wenger will spend the money - reported to be in the region of £30-50 million - wisely.
"They said they'd never cope without Thierry Henry or Patrick Vieira, but they didn't exactly drop like a stone. Cesc is a bit different, in that the other two were getting on a bit, while he's still a kid.
"But if Arsene spends that money wisely - and I'm sure he will - then he could bring in two or three who make the difference. Let's be honest, it's a dream move for Fabregas and, as much as Arsene would love to keep him, once a player's made up his mind it is very, very difficult to stop."
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