Brendan Rodgers has admitted it was difficult to leave Maik Nawrocki and Johnny Kenny out of his Celtic squad for the Scottish Cup semi-final.
Neither the centre-back or the striker feature on the bench for Celtic as the number of subs is eight in the cup competition compared to nine for league fixtures.
The Celtic boss cited the rule in his pre-match interview on BBC Sportsound as he admitted he "didn't quite get why" the sub rules were different.
"It's always difficult, it's the job of the manager and you have to deal with that," said Rodgers of making his team selection and leaving players out.
"And we've got two players who aren't even in the squad today, we have a man less on the substitute bench.
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"I don't quite get why you go from eight subs in the Scottish Cup to nine in the league.
"We lose two players in Johnny Kenny and Maik Nawrocki who have been absolutely brilliant in training and working so hard and they are not even on the bench.
"I am fortunate I have a fantatsic squad who are pushing. The players know if they are on the side they have to be ready to impact the game."
Celtic starting XI: Sinisalo, Johnston, Carter-Vickers, Scales, Taylor, McGregor, Engels, Hatate, Forrest, Maeda, Idah.
Subs: Bain, Trusty, Jota, Kuhn, McCowan, Schlupp, Bernardo, Ralston.
