Danny Lennon hailed his St Mirren players after they booked their place in the Scottish League Cup final.
The 3-2 victory against Celtic set up a Hampden showdown against Hearts at Hampden on 17 March.
"We're delighted," said Lennon. "I think this week it's been a fantastic effort from the backroom staff, with the preparation for the game, the tactics we've worked on.
"The players had the belief and showed their true potential."
Esmael Goncalves marked his Buddies debut with the opening goal, only for Gary Hooper to level before half-time.
Charlie Mulgrew had a penalty saved before conceding the spot-kick that gave St Mirren the lead a second time. Paul McGowan scored and Steven Thompson fired a superb volley before Mulgrew's late consolation.
"It's a fantastic achievement and fantastic result, but more important was the manner in which they've got the result," Lennon added. "That's for all our fans out there who've stuck by us through thick and thin."
Thompson said the players were in positive mood ahead of the tie and knew they could progress to the final.
"The quality of our play in the second half... we knew we could cause Celtic problems and we did," he said. "It's a magnificent feeling.
"I think there was (belief beforehand). I felt it this morning on the bus, in the changing room. I think the first 10 minutes gave us a lot of belief.
"We created chances, scored the goal - these things give you great belief. I think it had been so long since we scored against Celtic that it just gave us the belief that we could do this."