International Friendly: Czech Republic 2 Canada 0
The two sides had only met once in their history, with the Czech Republic romping to a 5-1 success in Teplice in November 2003.
And they produced a solid performance at the Andruv Stadion in Olomouc, as Canada's winless run was extended to 13 in all competitions.
The visitors made the worse possible start with Celustka heading home after just three minutes, but could have gone in level had Dwayne De Rosario levelled from the penalty spot, but he saw his effort beaten away by Petr Cech.
And Canada were punished in the second half when Horava calmly slotted home the second following a flowing move.
Interim Czech boss Josef Pesice handed a first start to Celustka, with Aston Villa's Libor Kozak leading the line. Benito Floro named Eintracht Braunschweig forward Simeon Jackson in his Canada XI.
Czech Republic applied the pressure right from the off and were rewarded in just the third minute.
Ladislav Krejci chipped a free-kick to the right-hand side of the six-yard area and Celustka rose highest to head home to the far corner.
The home side looked to build on their electric start and almost doubled their lead in a carbon copy of the opener, but this time Celustka failed to make good contact and Lars Hirschfeld easily held onto the ball.
After a slow opening, Canada started to settle into the game and in the 20th minute Tosaint Ricketts met De Rosario's cross with Cech making the save.
And they had a great chance to level proceedings six minutes before the break when De Rosario was felled in the area. Canada's captain stepped up to take the spot-kick but Cech was equal to the task as he dived to his right to make a strong save.
Czech Republic started the better of the two sides in the second half, and the lead could have been doubled in the 64th minute when Matej Vydra's left-footed strike forced Hirschfeld into a smart save.
But the home fans did have a second to celebrate with eight minutes remaining, when Canada were caught by a flowing counter-attack with Horava coolly slotting past the goalkeeper from inside the penalty area.