Luis de la Fuente insisted that his Spain team were continuing to push for more glory after matching Vincente Del Bosque's unbeaten streak with their victory over Bulgaria. 

Mikel Merino's brace, along with an Atanas Chernev own-goal and Mikel Oyarzabal penalty, sealed a 4-0 win for La Roja at Estadio Municipal Jose Zorrilla on Tuesday. 

Spain made it four wins from four in their World Cup qualifying campaign, with De La Fuente's European champions top of Group E by three points ahead of Turkey. 

They face Georgia and Vincenzo Montella's side in the next international break, knowing at least one victory will confirm their spot at FIFA's flagship tournament next summer. 

But their latest triumph came with significance. 

Excluding friendlies, Spain's men's national team have now not lost any of their last 29 international matches (W24 D5), equalling their best unbeaten run in history, achieved between 2010 and 2013 under World Cup-winning manager Del Bosque (G29 W24 D5).

"Don Vicente del Bosque is a reference for me. It's a reason for joy, and it's a success for the players. I value it. They are insatiable and want more," De la Fuente said.

"We want the 30th game, and the 31st, without losing. We want more, and we are optimistic about the future.

"We are the product of what we have inherited at a family and sporting level. Since 2008, with Luis, and then Del Bosque, they have left a legacy that helps the players. 

"Culturally, they know this story and that motivates us a lot. When you give them the incentive to compete, they are even more motivated."

But despite being on the cusp of booking their spot at the World Cup in the United States, Canada and Mexico, De la Fuente remained cautious for their next two fixtures. 

"There are two difficult games left, against Georgia and Turkey," De la Fuente added. "We have to do our homework and they are difficult opponents.

"We have to do things even better, and I'm sure we can. I've been saying for a long time that, at the national team level, nothing is easy.

"And I like it when they make it difficult for me. Minimising rivals is not easy. Any equipment can cause you problems. We are solving it little by little, but we have to continue".

However, with Arsenal forward Merino in fine form, Spain have every chance of reaching the World Cup. 

Indeed, Merino has now scored six goals in four matches for Spain in World Cup qualifying. No midfielder in the UEFA section has more (Kevin De Bruyne also has six). 

The 29-year-old also ended the match with team-high totals for touches in the opposition box (12) and chances created (five), leaving De La Fuente comparing Merino to the likes of Spanish superstars Rodri and Pedri. 

"He is an exceptionally complete player with great adaptability," De la Fuente said. "There are few players as versatile as him, and it is a privilege to have him with us.

"He reads opponents and situations superbly. He is a fantastic footballer, on the same level as Pedri, Oyarzabal, Rodri. We have an outstanding squad."