Mascherano left Liverpool for Barca in the summer of 2010 as a defensive midfielder but has since been converted into a centre-back in Catalonia.
And the Argentina international suspects that had he not made a crucial last-ditch challenge on Bendtner in the Champions League last-16 second-leg clash with Arsenal in March 2011, things could have been a lot different for him.
"Honestly, after five, six months I thought it was unlikely I’d be here long," Mascherano told the Guardian. "My characteristics seemed to go against everything Barcelona stood for.
"That moment marked me. If Bendtner had controlled the ball and gone the other way, he’d have got away from me and I don’t know what would’ve happened.
"But it happened the way it happened and we ended up winning that Champions League. Things worked out well."
Arsenal, who face Barca in the first leg of this season's last 16 on February 23, were trailing 4-3 on aggregate when Bentdner was put through by Jack Wilshere for the chance to score the away goal which would have sent the Gunners into the quarter-finals.
But Mascherano's tackle denied Bendtner and Arsenal and the 31-year-old has since come to be regarded as one of the best defenders in the world.
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"I actually played that game in midfield," Mascherano added. "It was Busquets who played at centre-back. But from then on, I played at centre-back: that tackle changed everything.
"I found my position and I’ve been there all these years, trying to keep my place and keep this level. Until when? I don’t know because Barcelona demand a lot and have the possibility to sign whoever they want."