Two of the World Cup's leading contenders will meet in Madrid on Tuesday but neither Spain nor Argentina have yet settled on a forward line for this summer.
For Argentina and Jorge Sampaoli the question is who best to stir Lionel Messi, with the two-time winners again boasting an embarrassment of riches up front, while showing little indication they know how to deploy them.
The supporting trio of Gonzalo Higuain, Sergio Aguero and Angel di Maria could reunite in Russia but they have disappointed together before, when all were younger and arriving in better form.
Meanwhile, Paulo Dybala, one of the game's most exciting young forwards, faces a fight for inclusion after being left off Sampaoli's latest list, and Mauro Icardi is expected to find his 26 goals for Inter Milan this season insufficient to make the squad.
Argentina may have to continue their search at the Wanda Metropolitano without their key component as Messi has been struggling with pain in his hamstring and adductor.
He trained on Sunday but is unlikely to be risked.
"Spain already has its team and knows how it will play at the World Cup," Sampaoli said. "We have to find that certainty."
"He told me: 'If you do not play, you cannot come'. But he also told me that when I played again, if I did it right, I had the doors open."
"It has been a great night both individually and collectively," Moreno said after his goal against Germany. "The next squad is the most important and everything will depend on what happens from here to the end of the season."