Nuno Espirito Santo's side, now devoid of Mateus Fernandes (Tottenham Hotspur), Crysencio Summerville (Al Hilal), Freddie Potts (Club Brugge) and Callum Wilson (Brentford), have enjoyed a successful pre-season and remained unbeaten throughout.
Decent pre-season for the Hammers
After their behind-closed-doors win over Colchester United, the Hammers went on to win 5-0 at Stevenage, before draws against Southend United, Rangers and 1. FC Magdeburg.
Even more important than their pre-season form was the knowledge that some of the club's big hitters were committed to staying, despite the drop into the second-tier.
Captain Jarrod Bowen, Tomas Soucek, Dinos Mavropanos, and Taty Castellanos have all remained, and whilst only Joel Veltman and Keiber Lamadrid have signed permanently so far this summer from Brighton and Deportivo La Guaira respectively (the latter after a loan spell at the Hammers which began in January), the East Londoners still have one of the strongest squads available.
Up against Portsmouth and in front of over 50,000 season ticket holders that are understood to have renewed over the summer, the claret and blue faithful will be expecting a decent home win to extend the positivity created by the pre-season performances.
Portsmouth looking for a big scalp
Not forgetting that things also seem a lot healthier off the pitch than they have in a long time, with Daniel Kretinsky saying and doing all the right things, and Amanda Staveley's PCP Capital Partners looking to get in on a slice of the action. That's a far cry from the ownership of disgraced former chairman David Sullivan.
Portsmouth were knocked out of the Carabao Cup at this stage last season, whilst also finishing in a lowly 18th place in the Championship, and will therefore be keen to take one of their biggest scalps at the earliest opportunity.
Their pre-season saw some mixed results, with the seven friendlies played producing two wins, three draws and two defeats.
It's the first fixture of any kind between the two teams since the match at Fratton Park during January 2012, which West Ham would win 1-0 on their way to promotion to the top-flight.
No extra-time
The last time the Hammers entertained Portsmouth in East London (September 2011) saw an epic seven-goal thriller, which the hosts edged 4-3, and Saturday's match will be the first time that they've met in the Carabao Cup.
Whoever comes out on top will edge in front on the head-to-head, as both teams have currently won 26 games each, and 13 have been drawn.
With no extra-time in these matches, too, the onus is on both teams to finish the tie inside 90 minutes, or else face the dreaded lottery of a penalty shoot-out.
No VAR might also be considered a welcome change by Hammers supporters, though goal-line technology will still be in evidence.
Pompey need an immediate impact from new signings
For Pompey, their XI could look a fair bit different from the one that ended 2025/26.
That's because over the summer, the club have signed all of Daniel Bielica, Rocco Shein, Odin Bailey, Luke Brooke-Smith, Eoin Kenny and Marko Milovanovic to bolster their ranks.
Of those, the 22-year-old Milovanovic, signed from Almeria, seems to be generating the most interest at Fratton Park, and has been compared to a younger Aleksandar Mitrovic.
High praise indeed for a player who came through the youth ranks at FK Partizan, but who might initially struggle with the physicality of the English game.
Manager John Mousinho will clearly be looking for an immediate impact from him and those players who begin the game, and where better for his charges to make their mark than at the London Stadium.
For Nuno, he'll be without the services of the hard-working Soucek, as the Czech continues his recovery from an ankle ligament injury, but the squad has a relatively clean bill of health otherwise.
With no defeats against Pompey in their last six head-to-heads, the hosts will feel confident of starting the new season in the best possible way.
Follow the match with Flashscore here.
Jason Pettigrove has been the features writer for Flashscore since 2025, utilising Opta data to form the basis of his articles. He has previously worked for high profile football clubs, news and media outlets, both in print and digital, and can usually be found watching FC Barcelona when time permits. You can read more of his pieces here.
