The 18-year-old defender played in the Bhoys’ Europa League Group A clash against Norwegian side Molde on Thursday evening.
The teenager started the match at Celtic Park and played for the entire 90 minutes, but he was left on the substitutes’ bench for Sunday’s league match against County at the Global Energy Stadium.
Tierney did not come on as a substitute, and Celtic manager Deila has explained his decision not to use the youngster.
“Kieran Tierney didn’t play today as he was very tired after last week’s game, and you cannot have too many players on the pitch who you know you’ll need to take off,” the Norwegian told The Scottish Sun.
Celtic did not have much trouble against County without Tierney, as they won 4-1. Tom Rogic, Leigh Griffiths (two) and Nir Bitton were on target for the Bhoys.
The Hoops are at the top of the Scottish Premiership table at the moment with 35 points from 14 matches, six points clear of second-place Hearts.