Southampton's hopes of reaching the Europa League's knockout stages have been left in the balance after a 1-0 defeat at Sparta Prague.

A familiarly ineffective performance against a team they had beaten earlier this season means they must at least draw at home to Hapoel Be'er Sheva in December if they are to qualify.

Costa Nhamoinesu's early goal proved enough to ensure Sparta will finish top after their fourth successive European victory, and that Southampton had lost their chance of being seeded.

Despite rotating his team amid the potential opportunity to secure their place in the competition's knockout stages, the only surprise in Claude Puel's selection came in his decision to name Oriol Romeu a substitute.

Nhamoinesu's early strike knocked the wind out of Southampton's sails (Getty)

Like only Virgil van Dijk and Fraser Forster, the midfielder has started almost every match since Puel's appointment, but it was again Charlie Austin's presence on the bench that was most influential.

Puel has spoken of Southampton's need to ease the goalscoring burden on the striker who has provided five of their paltry 12 league goals. Without him, however, they rarely look likely to score.

They threatened in only the third minute when Shane Long and Jordie Clasie combined with some one-touch football to put Jay Rodriguez into space in the penalty area.

Yet when the forward should have followed their lead and shot first time, he took the heaviest of touches and as in last month's 1-0 defeat at Inter Milan wasted a fine early chance.

In a match that had yet to settle it was unclear how damaging that could prove to be, but eight minutes later an indication was given when the hosts took the lead.

Southampton made seven changes to the side that started the goalless draw with Liverpool last weekend (Getty)

From what appeared a routine free-kick, Borek Dockal crossed towards Costa, who after a well-timed run sent a side-footed finish beyond Forster at the goalkeeper's near post.

Southampton's dominance of possession consistently led to little, and in a short spell mid-way through the second half the game came close to going beyond their reach.

The impressive Dockal's 58th-minute inswinging free-kick from midfield eluded everyone before forcing Forster into a reaction save. Lukas Marecek also went close shortly afterwards, and then a mix up between the usually-reliable Van Dijk and Maya Yoshida presented Dockal with another shooting opportunity the diving Forster palmed away.

Inevitably, Austin was brought on, but the suspicion was Puel's decision to delay using the striker until the 72nd minute would come at a cost, and so it ultimately proved.

Southampton came no closer to scoring, and perhaps worryingly for their hopes against Hapoel, the Israelis fought back from two goals down to defeat Inter 3-2.