AC Sparta Prague secured their place in the Europa League round of 32 after defeating Southampton 1-0 in Group K at the Generali Arena.
Costa Nhamoinesu’s early volleyed-goal from a free-kick at the near post was the difference between the two sides.
Southampton must either win or earn a goalless draw against Hapoel Be’er Sheva at St Mary’s on 8 December if they want to advance in the competition.
Hapoel Be’er Sheva completed their come-from-behind victory over Inter Milan with a goal late in stoppage time to draw level on seven points with the Saints.
After mixed opening exchanges including near defensive lapse for either side, Costa took advantage of a miscue as he guided Borek Dockal’s free-kick past Fraser Forster on 11 minutes.
Sam McQueen then struck a dipping left-footed effort straight at the Sparta keeper five minutes later with Southampton hoping for an immediate equaliser.
Tomas Koubek was called upon again when Shane Long found the end of James Ward-Prowse’s 19th-minute free-kick, but the save was easily made.
Despite having just a fourth of the possession, Vyacheslav Karavaev nearly doubled the lead only for Forster to parry the shot away on 56 minutes.
Forster made a reaction save to keep out Dockal whose free-kick moments later evade its intended target before running towards goal.
Southampton had little to show for their five corners and Virgil van Dijk header over the bar 10 minutes from full-time.
Sparta Prague: Koubek, Costa, Kadlec, Mauch, Karavaev, Holek, Marecek, Holzer (Dudl 90), Julis (Kostl 90+4), Dockal, Lafata (Havelka 88).
Unused subs: Miller (GK), Mil. Kadlec, Majka, Novotny.
Goals: Costa (11).
Bookings: Holek (32).
Southampton: Forster, McQueen, van Dijk, Yoshida, Martina, Clasie (Austin 72), Hojbjerg (Romeu 54), Ward-Prowse, Rodriguez (Boufal 55), Redmond, Long.
Unused subs: Lewis (GK), Bertrand, Stephens, Davis.
Referee: Jesus Gil Mazano.