Xhaka was outstanding in his side's shock penalty-shootout success over France in the round of 16, but the Arsenal midfielder's yellow card in the 76th minute means that he is suspended for this match.
As mentioned, Zakaria is expected to be handed a start in the middle of the park, but head coach Vladimir Petkovic could otherwise name an unchanged XI from the clash with the world champions.
Switzerland's back three were given a tough examination by France last time out, but unless there are any late injuries, the trio of Nico Elvedi, Manuel Akanji and Ricardo Rodriguez will again take to the field.
Mario Gavranovic came off the bench to score the late equaliser against France, but the 31-year-old is not expected to be in contention for a starting role against Spain.
Switzerland possible starting lineup: Sommer; Elvedi, Akanji, Rodriguez; Widmer, Freuler, Zakaria, Zuber; Shaqiri; Embolo, Seferovic
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