The two clubs met on the opening weekend of the season, when Liverpool triumphed 2-1 at Anfield thanks to Daniel Sturridge's winner 11 minutes from time.
That came despite a spirited performance from Southampton, who many people tipped to struggle after seeing a host of their star names depart - three of them to Liverpool.
For Adam Lallana, Rickie Lambert and Dejan Lovren, the match represents their first return to their former club, although Lallana is likely to be the only one of that trio given a starting role.
After being frustrated by Swansea City and West Ham in their last two home games, Koeman is expecting Liverpool to show more attacking intent.
"I think it's about teams. I don't expect Liverpool to come in that way on Sunday," he said in a press conference on Friday.
"We have to know that Swansea and West Ham didn't come to Southampton to play open and offensively. That brings difficulties and we didn't have the quality to break them down.
"This Sunday is totally different, but it's all about sharpness in the box, possibilities. I think it's a good time to score goals and create more opportunities than we did in the last two games."
Southampton come into the game fourth in the table, four points and three places clear of their opponents in the race for UEFA Champions League qualification.
They have lost one of their last nine league games, while Liverpool have tasted defeat only once in their past 17 outings in all competitions.
With that run of form boosting their hopes of a top-four finish, manager Brendan Rodgers says this weekend's clash is an important one as they look to move to within a point of Southampton.
"They've kept their momentum going over the last five seasons," he said. "They've found themselves in the top four and deservedly so.
"With 13 games to go, it would be a big step for us to get a result. We know we've got the quality and confidence to go there and get a result. We need to keep edging towards it [the top four]."
Rodgers confirmed that captain Steven Gerrard (hamstring) would be unavailable, which could lead to another on-field debate should they be awarded a penalty after Mario Balotelli took the ball off Jordan Henderson for a crucial spot-kick in the 1-0 UEFA Europa League win over Besiktas on Thursday.
For Southampton, Koeman said Shane Long and Morgan Schneiderlin were looking "positive" after respective rib and groin problems, although Toby Alderweireld is still out with a hamstring injury and Ryan Bertrand serves the last game of a three-match suspension.
