Spaniard Sarabia headed home the only goal with 10 minutes remaining to put Thomas Tuchel's much-changed side into the next round after struggling to break Ligue 2 leaders Lorient down in an underwhelming contest.
They have been rewarded with a tie at third-tier Pau, who knocked out Ligue 1 side Bordeaux on Thursday.
PSG came into the match missing a host of injured stars including Edinson Cavani, Marco Verratti, Juan Bernat and Marquinhos, and with both Neymar and Kylian Mbappé on the bench the away side lacked creative spark despite the presence of in-form striker Mauro Icardi.