After a group stage in which things did not always go to plan for Spain, they will hope for a fresh start in the round of 16 when they take on hosts Russia at the 2018 FIFA World Cup.
La Roja topped Group B but picked up just one win, against Iran, as Portugal and Morocco held them to high-scoring draws.
Russia beat Saudi Arabia and Egypt before losing to Uruguay to finish second in Group A.
Date: Sunday, July 1
Time: 3 p.m. BST/10 a.m. ET
TV: BBC (UK), Fox (U.S.)
According to Marca's Jose Felix Diaz and Miguel Angel Lara, Spain boss Fernando Hierro could be set to replace Thiago Alcantara with Koke, while Marco Asensio could also be brought in to start.
Per Tom Doyle of the Evening Standard, Aleksandr Erokhin could be available for Russia after a foot injury, while Alan Dzagoev—who limped out of their first match early on with a hamstring injury—has returned to training.
Igor Smolnikov was sent off in Russia's most recent match, so he will be suspended on Sunday.
Spain were firmly among the tournament favourites before it began, but Julen Lopetegui's sacking on the eve of the World Cup appears to have unsettled La Roja.
They were unconvincing at the back throughout the group stage, not only against the threat of Cristiano Ronaldo but also against Morocco, who found the net twice.
ESPN FC's Dermot Corrigan believes they could still go far if they can improve, though:
Although they struggled to break down Iran in their second group-stage match, La Roja have been more impressive going forward.
Diego Costa scored twice against Portugal, while Iago Aspas saved their blushes with a last-minute backheel flick against Morocco.
As football journalist Alexandra Jonson noted, Aspas perhaps deserves to be used more often by Spain:
Russia's chief threat will be Aleksandr Golovin. He was rested for the hosts' 3-0 defeat to Uruguay, but he played a key role in their victories over Saudi Arabia and Egypt.
Bleacher Report's Sam Tighe praised the CSKA Moscow midfielder's contribution as he provided two assists and a goal in against the Green Falcons:
Sam Tighe @stighefootball
FT #RUS 5-0 #KSA. An incredibly easy start for Russia. Still difficult to gauge their strength due to how poor Saudi Arabia were. Golovin (MOTM) rinsed them in the channels + when surging into space. Ran his socks off and that free kick 😮. Cheryshev with two beauties! #WorldCup
Spain will be much more of test of his abilities than they were, though, so it will be fascinating to see how he fares against stronger opposition.
La Roja should be able to win here, and progressing is the priority. But they will also hope to restore some confidence with a stronger performance than they have thus far conjured.