Jordan Rhodes' injury-time winner made it a good week for Rovers with seven points from their three games to consolidate their place in the top five of the npower Championship.
Rovers had to be patient against a well-drilled Watford side and after Colin Kazim-Richards missed from the penalty spot it loked like it would be an afternoon of frustration until Rhodes fired home in added time.
"It was always going to be tough and we knew that with the way Watford were structured," said Black on Radio Rovers after the game.
"They defend the ball very deep, you need to be patient and they play on the counter and have really decent front men.
"We had to be patient, we had to be disciplined, and thankfully we've scored at the end.
"I think today every single one of them deserved the credit because they were really patient, they worked tirelessly and eventually we've ground them down.
"I thought our attitude was outstanding, even Kaz, after he's missed the penalty, I thought his reaction after that was fantastic.
"So it is all credit to the players, they've got their rewards today.
"If it can't be in the first minute, lets make it the last."
Rovers had worked hard throughout but with little reward and when Colin Kazim-Richards put a 77th minute penalty against the crossbar, you felt it wasn't going to be their day until £8m man Rhodes turned to clinch all three points with his fifth goal for the club.
"I thought it was a magnificent finish," added Black. "Again Jordan has worked tirelessly the whole game and has had very few chances but one falls to him and the quality is shown.
"His chances to goal ratio is exceptional."
Rovers are back in action next Saturday at Selhurst Park when they take on Crystal Palace.