Zola praised the way his players carved out their opening day success and paid credit to his striker Troy Deeney for his top-quality goal.
Deeney demonstrated his lethal finishing skill in style when he notched Watford's 11th-minute winner.
It was a clinical goal and highlights Denney's value to the high-performing Watford side.
In the closing stages of the game it was Watford's defence which had to pull out all the stops as Birmingham surged forward in a desperate bid to grab the equaliser.
Zola said: "I am pleased with the win. It was a tough test to start the season. This is why I am pleased with result and the performance.
"In first half we were excellent for long spells. Perhaps we should have tried to have taken more chances and scored more than one goal.
"Birmingham came back stronger in the second half. We dropped a little bit physically and we allowed them to cause us a lot of problems.
"We demonstrated we are working really well, particularly in the defence. I am looking forward to see a lot more of this kind of play during the season.
"I thought we were good to watch and attacked the space instead of holding the ball.
"But the application was excellent and I am looking to see it more and more during the season."
Zola admitted that there was no need for him to motivate the players after the disappointment of play-off defeat last season.
He said: "Everyone feels we are better prepared as we have more knowledge of the difficulties and we are looking forward making a strong challenge.
"There are some good teams in the Championship and it will not be easy. But our attitude is very good and I thought Deeney took his goal exceptionally well.
"His combination with Forestieri was good. In some spells they were outstanding.
"We believe if we are to make the top flight we have to be well prepared. But I do think we now have a stronger team than lastly season."