Israeli minnows Hapoel Be'er Sheva earned a 1-1 draw at St Mary's as Southampton were knocked out of the Europa League.
Maxime Le Marchand scored the game-winner for Nice who concluded their Europa League run with a 2-1 win over Krasnodar.
Xaver Schlager helped Salzburg to a win in their final group stage game against a Schalke team that finished top of Group I.
The hosts had needed a goalless draw to progress to the last 32 of Europe's second-tier competition.
John Guidetti's header proved to be the game-winner as Celta defeated Panathinaikos to advance to the round of 32.
Celta Vigo claimed their place in the last 32 of the Europa League with a straightforward 2-0 win over Panathinaikos in Athens.