The Seagulls became champions with four games to spare after Saturday's 3-1 win away to Walsall and their first game as title-winners will be at home to Saints on Saturday.
Winger Lallana, one of five Southampton players selected in the PFA League One Team of the Year, told the Southern Daily Echo: "They have already been crowned as champions, so hopefully they have had a heavy week and we will catch them on a bad afternoon.
"It is a massive game for us, but we will prepare as normal and hopefully we will get the three points.
"We have five games left and hopefully we can maintain our good form and get promoted."
Source: PA
Source: PA