"The standard of the opponents goes up from the reserves but you just have to get on with that and not worry about it."
Celtic boss Gordon Strachan is unsure whether Boruc will make the clash with the Ukrainians and hinted it could be another last-minute decision.
Brown is ready to seize his opportunity if it comes along. He said: "Of course you would want to play in the Champions League - it's a great competition.
"I would love to be involved but I will just prepare as normal. On Monday and Tuesday I will wait and see how Artur is and take it from there."