Fernando Llorente's World Cup debut for Spain played a big part in turning around the team's fortunes against Portugal.
Llorente replaced the fading Fernando Torres in the 59th minute Tuesday, and his introduction changed the dynamic of Spain's attack against Portugal.
Four minutes later, David Villa scored the goal that sent the European champions into the quarter-finals with a 1-0 victory.
Portugal was forced to adapt its defence to Llorente, the strong and lanky Athletic Bilbao striker who had two headed chances just miss during his half hour of play.
"They opened up and it gave us chances," Llorente said, "so we adapted."
The goal provided Spain with the security it needed against a stubborn opponent, and it comfortably controlled the match to the close to reach the quarter-finals for the first time since 2002.
"I spent a lot of time imagining this moment," said Llorente. "To go out and have a header chance just after that, and then [for us] to score right after was amazing."
Llorente has scored three goals in his eighth appearance under Del Bosque, who recalled the Pamplona native for the World Cup for the first time since last year's Confederations Cup. The 25-year-old has scored 41 goals for Bilbao over the past two seasons to establish himself among Spain's top strikers.
"He's a special player," Del Bosque said. "We needed someone who could hold the ball, who could protect it because they had six very tall players. In any case, the credit shouldn't go to the coach but to those who go out onto the field."
Some Spanish newspaper websites have opened up a new debate ahead of the Paraguay match: should coach Vicente del Bosque start Torres or Llorente?
While Del Bosque said Torres will play against the South Americans, Llorente's arrival provides a different attacking option that has also left midfielders Cesc Fabregas and David Silva further out of the playing picture.
Silva didn't feature for the third straight game and Fabregas watched the entire 90 minutes from the substitutes bench. The Arsenal playmaker, instrumental in the Euro 2008 triumph, has played only 59 minutes in South Africa and was the only Spanish player who didn't sprint onto the Green Point Stadium field to celebrate the Portugal victory.
"We've followed the path marked by former players and coaching staff," Del Bosque said. "We've made alterations but always following the same line."
With a likely defensive-minded Paraguay awaiting, Llorente could get another call.
"We shouldn't start thinking that Paraguay is an easy rival," said Llorente, whose full name is Fernando Llorente Torres. "Let's see if we have luck like today and that everything works out like it did against Portugal."