Duff moved to the Parkhead side in a coaching capacity in January 2019 and has helped Celtic to two league titles as they were recently confirmed 2019-20 champions to equal the record of nine league wins in a row.

And while it was unclear as to whether the former Chelsea, Blackburn and Newcastle winger would combine his role at Celtic with his new national team position, Bhoys boss Lennon has confirmed the Dubliner's departure.

"I spoke to Damien on Monday and he was in good spirits but he'll join the FAI," said Lennon. "It’s a blow because he contributed immensely and personally I got on great with him.

"He's in his formative years as a coach but he made a huge contribution and there was a good chemistry there. So he’ll be difficult to replace, that’s for sure.

"We were waiting on everything getting called first then we’ll look to replace him but it’s not at the forefront of our minds."