Spain coach Julen Lopetegui says he could use a range of players at No. 9 for the 2018 World Cup in Russia.
Alvaro Morata, who has scored seven goals and set up three more in 10 Premier League appearances since joining Chelsea from Real Madrid in the summer, and Diego Costa finished as the top scorers in qualifying with five goals apiece.
Celta Vigo's Iago Aspas, Valencia's Rodrigo and Athletic Bilbao's Aritz Aduriz have also played at centre-forward for Spain and Lopetegui is happy to use a range of attackers.
"Morata is a very good No. 9 that we have and we are very happy with him," Lopetegui told Cadena Ser. "Rodrigo is, too, and so is Aspas. Diego Costa will be, too, once he joins us.
"When the time comes, we will decide who our No. 9 player will be for our first game. It may be that we will not play with the same No. 9 for our second game. We shall see. They all have possibilities to be the starting No. 9 for Spain."
Costa has not featured for Spain since June 11 and missed the national team's final four qualifiers after a dispute with his then club Chelsea.
The Brazil-born star has since resolved his future by returning to Atletico Madrid but cannot play until January 2018, resulting in his omission from Spain's squad since the summer.
Spain qualified for the World Cup by winning nine and drawing one of their 10 group games while scoring 36 goals and conceding just three.
Lopetegui insists the door is not closed to anyone looking to break into Spain's World Cup squad but says there are not going to be wholesale changes to his current selection.
"There are many here that will be in Russia," he said. "But I would lie to you if I told you that I have clear the 23 players that will go to the World Cup. There are some that, unless something unexpected happens, are certain to have a spot and others that have an excellent opportunity to make us doubt."
Liverpool left-back Alberto Moreno has returned to the Spain squad after a three-year absence thanks to his impressive early-season form.
The 25-year-old made just two Premier League starts in the 2016-17 campaign after losing his position at left-back to James Milner but reclaimed his starting position this season.
"I knew Alberto from our time in the Spain under-21 squad," Lopetegui said. "We had doubts on whether to bring [Chelsea left-back] Marcos Alonso or Alberto but in the end we decided to bring the latter.
"He didn't have a good year last season. It looked like this season things were also going to be complicated for him because of his club's decision to sign another left back [Andrew Robertson] during preseason but he took a gamble, he decided to stay at the club and now he is an undisputed starter.
"He is a left-back that suits us, someone that is eager to go forward, and is also very fast at correcting his position. He is accustomed to playing in that role at Liverpool."
Lopetegui said the upcoming friendlies are very important for the World Cup preparations. La Roja host Costa Rica in Malaga on Saturday before taking on Russia three days later in St. Petersburg.
"I'm convinced that in order to do something great at the World Cup you can't start to prepare a month before the tournament," the 51-year-old said. "We have to start feeling it now and make the most of the two games that we have. We have to consolidate the good things we have done so far and improve on other aspects.
"We need to keep growing as a team. Whoever wants to do something special at the World Cup, besides having great players, they will need a great team."