Sevilla's incredible run at home finally came to an end as they were beaten 2-1 by 10-man Real Sociedad, halting a run of 13 straight Primera Division wins.
Markel Bergara headed the Basques in front after just two minutes and Grzegorz Krychowiak's own goal doubled their advantage before the break.
Kevin Gameiro pulled one back from the penalty spot early in the second half and Bergara was sent off on 67 minutes for a second booking - but an equaliser remained elusive.
Sevilla are the only team in the league without an away win but they have stayed among the Europa League places due to their imperious home form.
But they got off to a nightmare start here, failing to track Bergara, who leaped to head Illarramendi's free kick into the top corner.
Sevilla struggled to deal with La Real's high pressing game, although two chances to level fell the way of Kevin Gameiro in the space of a couple of minutes around the half-hour mark - but he was denied by the quick reactions of goalkeeper Geronimo Rulli.
They were punished at the other end by another deep free-kick by Illarramendi, Krychowiak failing to communicate with Sergio Rico and putting it into his own net.
Sevilla found a way back into the game when Adil Rami was pulled down in the box by Bergara, who earned his first booking.
Gameiro powered his shot past Rulli and the tide again turned in Sevilla's favour when Bergara was shown a second yellow for a late tackle on Ever Banega, but they could not take advantage.
Sevilla stay seventh in the table, while Real Sociedad climb to 10th.
ends