Barcelona suffered a double injury blow in their 2-0 Spanish Super Cup win away to Sevilla on Sunday with Andres Iniesta and Jeremy Mathieu coming off before half-time.
The Catalan giants scored twice in the second half through Uruguayan striker Luis Suarez and Munir El Haddadi but Iniesta and Mathieu's injuries cast a shadow over the first competitive game of the season for Barca.
Defender Mathieu pulled his hamstring and was taken off in the 27th minute, before Iniesta joined him on the treatment table shortly afterwards, following a strong challenge from Sevilla defender Mariano in the 36th minute.
New signings Lucas Digne and Denis Suarez came on in their place to make their club debuts.
The second leg will be played on Wednesday at the Nou Camp before Barca open their La Liga title defence at the same ground against Real Betis next Saturday.