On the other hand, Tierney has made just two appearances in the Scottish top flight in his career, one of which has been as a late substitute.
The teenager made his full debut for Celtic only on Friday evening, when he started the Premiership encounter against St Johnstone away from home at McDiarmid Park in Perth.
Prior to the match, which ended in a goalless draw, Deila made a bold claim about the future of 17-year-old Tierney on BT Sport.
“He is a very promising youngster,” said the Norwegian. “He has been good in training for a long time. I wanted to give him a chance also for a long time, but he has been a little bit injured…
“Yes, he has (the ability to push Izaguirre). He is ready for this level. He shows that in training every day, and he has also played some good games for the Under-20s.”
Tierney, a Scotland Under-18 international, is a highly-rated left-back who can also play as a left-winger.
The youngster is best suited to attacking, with his pace and crossing ability impressing many who have watched him play for Celtic’s Development Side this season.
The Scot is still learning and developing his game, but it seems that Deila has confidence in the 17-year-old’s ability to establish himself as a first-team regular in the coming years.