'Tierney can be the best left-back in the world'

Tierney's rise from academy graduate to first-team star caused Izaguirre to lose his place in the team at Celtic Park, with the Honduran eventually moving to Sauri Arabia in search of first-team football.

However, the 32-year-old has now returned to the Scottish champions, with a pledge to help ensure Tierney reaches his immense potential.

"I'm very happy as Tierney is my boy," he told the Celtic website.

"I always tried to stay in touch with him and help him - and I'm happy to help him progress. I want to help him become the best left-back in the world.

"He wanted to be a big player. He needs to continue to work hard and keep doing the things he did last year and he can be the best player in his position in the world."

Whilst Izaguirre is no doubt champing at the bit to get back involved as soon as possible, he admits that he will have to be patient.

"It was difficult for me as I wanted to try and play more, but, after one year, I understood that I never wanted to leave and it's more important that I try and help the team at Celtic," he explained.

"For me, it's important to help the team in any way I can, whether I play or not.

"My focus is to play any minutes when the gaffer gives me the opportunity and always to be positive for the team."