Spain coach Vicente del Bosque said his team played "too artistically" and could have scored more goals in Saturday's 3-0 win against Belarus.
Goals from Isco, Sergio Busquets and Pedro Rodriguez carried Spain to victory, but La Roja also missed a number of chances to make the scoreline even more one-sided.
Pedro wasted an opportunity in the first 10 minutes as the Barcelona man fired a first-time effort wide with only goalkeeper Yuri Zhevnov to beat. Spain also struck the woodwork twice in the match.
Del Bosque said he was satisfied with the win but that his side need not try to set up every play perfectly.
"We played well, we dominated the game and in less than half-an-hour we scored two goals," he said. "We hurt the match because we wanted to play too narrow and too artistically.
"Isco played well but he got caught up in doing things that depended on the fine margins. But we're not a team that usually gets goals from outside the box and we did here so that should boost morale.
"We were comfortable, we were convincing at 2-0 and then we got carried away. But the game went well.
"The midfielders were very serious and if we find the strength of that core we have a lot to look forward to. Juanfran and Santi Cazorla linked up a lot and Juanfran got forward a lot. I think he can feel happy."
Alvaro Morata, a late substitute, was delighted to make his first appearance for the senior squad.
"I've fulfilled a dream. I have so many emotions I don't know what to say," Morata said. "The truth is I don't have a lot to say about it. I'm a little emotional."
Morata also praised the play of Isco, who was making his first start for the national team.
"It's like he has glue on his boot," Morata said of Isco.
Spain remain three points back of Group C leaders Slovakia, who defeated Macedonia on Saturday.