Charlie Austin could lose his place in Southampton's starting XI at home to Swansea on Sunday, despite his two goals in their Europa League win against Sparta Prague.
The Saints remain in pursuit of their first Premier League victory of the season but demonstrated their potential with a fine performance against the Czech side on Thursday night with a 3-0 win.
Despite making seven changes to the team that lost 2-1 at Arsenal last Saturday, Claude Puel refused to guarantee Austin would remain in his starting XI for this weekend's visit of Swansea.
Swansea head to the south coast having collected a hard-earned point in a thrilling 2-2 draw at home to Chelsea last Sunday.
After Southampton, Swansea have a cup and league double-header with high-flying Manchester City before Premier League tests against Liverpool and Arsenal.
Team news
Southampton will assess forward Jay Rodriguez ahead of Sunday's Premier League match.
Rodriguez came off the bench to score a last-minute goal in the 3-0 win over Sparta Prague, and manager Puel reported him as a fitness concern.
James Ward-Prowse could be back on the bench and club-record signing Sofiane Boufal remains out with a knee injury, as does right-back Jeremy Pied.
Swansea are set to return to a four-man defence on Sunday, and that could mean more disappointment for Neil Taylor.
The Wales international was hauled off before half-time of the 2-2 draw against Chelsea last weekend as manager Francesco Guidolin abandoned the experiment of playing three central defenders. Taylor could once again lose out to Stephen Kingsley, who has been first-choice left-back this season, at St Mary's.
Record signing Borja Baston could make the bench after a thigh injury which has delayed his debut since a £15.5m move from Atletico Madrid, but winger Nathan Dyer has been ruled out for two months with an ankle problem.
Match stats
Southampton have lost just one of their previous eight Premier League games against the Swans (W5 D2).
Swansea have failed to score in five of their last seven league games against Southampton.
All of Swansea's three Premier League goals against Southampton have been scored in the 73rd minute or later.
The last time Southampton failed to win any of their first five games in a Premier League season was in 2000/01.
Southampton are currently on the longest run in the Premier League without keeping a clean sheet (16 games).
Merson's prediction
This is a big game for both teams. Swansea did well to get a point against Chelsea but Lukasz Fabianski was very good.
At the same time, Southampton were unlucky at Arsenal. They played really well and should have got a point at least. It was a much better first half but they missed chances and got punished at the end.
They need to win this because they haven't won a game yet, and all of a sudden the pressure starts building on a new manager.
But Southampton are a better team than their league position shows and I think it will come on Sunday.
PAUL PREDICTS: 2-0 (Sky Bet odds 6/1)