Fresh from winning their 26th La Liga title, Barcelona have been upset by relegation-threatened Celta Vigo.
The Catalan side rested Lionel Messi, Luis Suarez and Gerard Pique for the match.
Goals from Maxi Gomez and Iago Aspas gave the Célticos a memorable and crucial win, moving them up to 14th in the table and five points clear of the drop zone.
Barcelona will now travel to Anfield to play Liverpool in the second leg of their Champions League semi-final second leg.
They hold a 3-0 advantage after the first leg.
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