Ronald Koeman has warned Southampton will come unstuck against Sunderland on Saturday if they fail to learn lessons from their defeat to AFC Bournemouth.
Koeman lamented a slow start at the Vitality Stadium on Tuesday, but Southampton were second best for long spells as they slipped to a 2-0 defeat against their south-cost rivals, losing strikers Charlie Austin and Shane Long to injury in the process.
Both will miss this weekend's game as Southampton host a Sunderland side out of the bottom three on goal difference and with just two away wins in the Premier League all season.
Saints sit ninth and Koeman says a European push is still achievable, provided he gets a response from his players.
"The Premier League is a tough competition," he said. "Look at the big teams - [Manchester] City, [Manchester] United, Arsenal, if you are not at 100 per cent you don't win. Every opponent is a tough one and you need to stay at your level.
"Fighting for Europe is still achievable for us but you need a good run, after two defeats we need to win and that's the pressure we have this Saturday.
"The start [at Bournemouth] was not good and if you start like that you'll have problems - that was my message to the players.
"But they're not stupid, they know what they can bring and what they need to bring."
Sunderland needed a late Fabio Borini strike to earn a point in a 2-2 draw against Crystal Palace on Tuesday and ended the midweek's action out of the bottom three as rivals Newcastle United lost at Stoke City.
Boss Sam Allardyce - who could welcome back Jeremain Lens following hernia surgery - says a point at St Mary's would represent a positive return from their lengthy trip south.
"At the end of the day we have to get a result against Southampton," he said on Thursday.
"To ask for a win is a very big ask on the basis that we haven't won many games away from home.
"But we had an opportunity to win away at West Ham [last weekend] and we turned it down. Southampton is a different kettle of fish and I think every game we play away from home we have to be on top form.
"We will have to find that form we displayed at West Ham, particularly in the second half, and be more clinical in front of goal to try and get a result."
Key Opta stats:
- Sunderland suffered their worst Premier League defeat in this fixture last season, losing 8-0.
- Saints have won none of their last 11 Premier League matches where the opposition have scored.
- Sunderland have gone 14 games without a clean sheet, the longest run of any team in the Premier League this season.
- Saints have lost three games where they have been leading this season - more often than any other Premier League team.