Luke Bryan Can't Tame the Hoarse During Concert

Luke Bryan all but lost his voice during his concert Saturday night ... but he distracted fans with his moves.

Bryan performed in So. Cal. at the Irvine Meadows Amphitheatre and warned the crowd in advance ... but they were undeterred.

Luke carted around hot tea, to no avail ... so he asked an obliging crowd for help singing.

A chest cold still looks good on him.