Mixed moods in each camp
Last season, Southampton and West Ham both enjoyed very successful seasons. While neither experienced anything close to Leicester's fairy tale story, they each achieved more than was probably expected from them by qualifying for the Europa League.
However, it has not been so simple for either side so far this time around, with both languishing in the bottom half of the table after the opening five games.
Despite this, the mood from each camp going into this 'clash of last season's over-achievers' could not be more opposing. For Southampton, pressure on new manager Claude Puel has eased following three wins in the space of week, all in different competitions, including a first league win of the season over Swansea.
As for Slaven Bilic's side, a combination of new signings, European football and a high-profile move to the Olympic Stadium meant there was plenty of optimism regarding the East London outfit as they entered a new chapter. Yet fast forward six weeks or so, and the positive mood has been shattered. A premature exit from the Europa League, followed by a poor start to their league campaign means West Ham's promising bubble has well and truly burst. Add the fact that they now sit in the relegation zone and are having crowd problems off the pitch means the Olympic dream is turning into a nightmare for the Irons.
A victory in the EFL Cup midweek has eased some of the pain for the Hammers after some atrocious results in the league, but Southampton will surely feel their hosts on Sunday are there for the taking. Can the Saints keep their good form going? Can West Ham turn the tide? It looks set to be a mouth-watering clash.
West Ham's poor form is partly down to their current injury list, and this week left-back Arthur Masuaku was added to it as he picked up a knee injury against Accrington on Wednesday. This leaves the home side without a recognised left-back, as Aaron Cresswell remains sidelined.
Centre-back Winston Reid is expected to return following missing the 4-2 defeat at West Brom last Saturday. Andre Ayew, Diafara Sakho and Andy Carroll are still unavailable.
As for the visitors, Southampton's only fresh injury issue is Jay Rodriguez's knee problem, which will keep him out of Sunday's game. In addition, Puel will be without right-back Jeremy Pied for the foreseeable future, as he continues to nurse a long-term knee injury. New signing Sofiane Boufal is still not match fit.
West Ham have the Premier League's joint top scorer (Michail Antonio), and top assist maker (Dmitri Payet), but have only mustered a single win so far this season.
Southampton haven't kept a clean sheet away from home since February.
West Ham have scored in every game in the Premier League this season. Southampton haven't scored more than one in a match so far.
There's history between them
In the sides' clashes last season, the home side came out on top each time. West Ham won 2-1 at Upton Park, before Southampton got their revenge at St Mary's with a 1-0 win.
Michail Antonio is the only player in either team to have played for both West Ham and Southampton.
The clubs have met 28 times in the Premier League era, with West Ham taking the three points on twelve occasions, compared to Southampton's seven.