Spain coach Luis de la Fuente said on Thursday that Belgium would provide his side's sternest test yet in the World Cup quarter-finals, with his team having reached the last eight without conceding a goal.
Among the favourites to lift the trophy, Spain booked their place in the quarter-finals with a 1-0 win over Portugal and have grown into the tournament with a balanced side that is comfortable in possession, solid in defence and boasts enough attacking quality to trouble any opponent.
"Tomorrow's game will be the hardest that we've faced to this point," de la Fuente told reporters in Los Angeles Stadium, pointing out that Belgium's experienced squad includes players with proven pedigree at some of Europe's biggest clubs.
"Belgium is a very powerful team. These are players who are used to winning. It's going to be a challenging match."
The winners of Friday's game in Los Angeles will face France in Tuesday's semi-final in Dallas after Les Bleus earlier beat Morocco 2-0, with goals from Kylian Mbappe and Ousmane Dembele.
Asked about the prospect of meeting France, de la Fuente said he watched the game and thought the French were the better team, but said Spain were completely focused on Belgium.
"Trust me we are only thinking about Belgium tomorrow," he said.
While Spain have looked imperious at the back, they are likely to look for attacking inspiration from 18-year-old Barcelona forward Lamine Yamal and Mikel Oyarzabal, who has already scored four goals at the tournament.
Lamine, regarded as one of the world's brightest young talents, has scored only once at the World Cup so far, well behind leading marksmen Lionel Messi and Kylian Mbappe, who have eight goals apiece.
However, de la Fuente said Yamal had shown growing maturity, pointing to the teenager's defensive contribution in Spain's win over Portugal, and backed his attacking quality to make the difference when it mattered.
"He's going to perform on the attacking front," de la Fuente said.
The coach added that Spain's success had been built on collective effort rather than individual brilliance, stressing that every player had put the team first.
“What is bad for the hive is also bad for the bee,” de la Fuente said, invoking a quote attributed to the Roman emperor Marcus Aurelius.