Marek Hanousek's hat-trick sent Celtic to a disappointing defeat in their second game of pre-season as Dukla Praha beat the Scottish champions 5-3.

The Czech midfielder was a constant thorn in Celtic's side at St Mirren Park on Saturday, scoring in both halves as Dukla inflicted the first defeat of the new campaign on Ronny Deila.

Hanousek opened the scoring after 13 minutes as Celtic's defence – which included new signing Dedryck Boyata – failed to close him down, the 23-year-old firing into the corner past Craig Gordon.

Leigh Griffiths levelled just before the half-hour after Mikael Lustig had been felled by Hanousek, but the latter quickly restored the visitors' lead as he pounced on a loose ball.

Celtic went into the break level when Gary Mackay-Steven was superbly found by Stefan Johansen, the forward cooly firing home to complete a goal-laden first period.

The goals kept on coming after the break as Hanousek got his hat-trick from the penalty spot, with Jakub Mares making it 4-2 on the hour.

Substitute Virgil van Dijk cut the deficit with a header beyond Filip Rada from Johansen's free-kick, before a sweet strike from Tomas Prikryl completed Dukla's victory.

Afterwards, Deila conceded his side had been given a real workout.

"We met a good team today and had a good test. We have a lot of things to work on," he said.