The Norwegian was impressed with the 18-year-old's Europa League display.
Indeed, the Norwegian insists the Scottish champions must take the positives from their 2-2 stalemate with the Turkish side, having surrendered a 2-0 lead against them.
And one of those positives was 18-year-old Tierney, who Deila feels had a 'very good' European debut.
The teenager caught the eye for Celtic at Parkhead, although the raucous home atmosphere couldn't inspire his side to a win.
RD: We have to take the positives from the game. I’m very happy with Kieran Tierney tonight. He had a very good European debut.— Celtic Football Club (@celticfc) October 1, 2015
Deila also praised skipper Scott Brown, who he feels was 'fantastic' and worked exceptionally hard against Fenerbahce.
It marks a significant improvement from the experienced midfielder, who received criticism both for his Celtic and Scotland displays a few weeks ago.
RD: Scott Brown was fantastic in the midfield, working really hard and keeping the team together.— Celtic Football Club (@celticfc) October 1, 2015
Next up for the Bhoys in the Europa League is a trip to Molde, before Celtic then host the same side at Parkhead.
They'll need to register their first win of the group stage soon but, after two draws, find themselves second in the table - meaning they are still in a good position with plenty to play for.