The Saints have had just one run-out so far this summer heading into this clash at the Cardiff City Stadium, while the Bluebirds are in action for a sixth time.
Southampton's first pre-season match was also against second-tier opposition, with Ralph Hasenhuttl's charges playing out a 1-1 draw against Fulham behind closed doors on Saturday.
Hasenhuttl used his now-trademark 4-2-2-2 formation and fielded effectively a different side in each half, with Salisu the only starter to feature in the second period.
The Saints now have three more friendlies, against Cardiff, Swansea City and Athletic Bilbao, before travelling to Everton on the opening weekend of the Premier League season.
Cardiff's Championship campaign begins a week earlier, meaning that the Welsh side are at a slightly more advanced stage in their preparations than their opponents.
Mick McCarthy's side kicked off their summer programme with a 5-0 win over Bath City, before losing and drawing with Cambridge United in two 60-minute matches.
A 2-1 win at Forest Green Rovers was then followed by a 2-2 draw against Exeter City on Saturday, making for a rather mixed set of results for the Bluebirds thus far.
Results are not the most important thing at this point, of course, but McCarthy now has just two games - against Southampton and Newport County - to get things right.
Skipper Sean Morrison has yet to feature this summer, but McCarthy expects the centre-back to play a part against either Southampton or Newport.
Given their campaign begins in less than a fortnight, the Bluebirds will go with a fairly strong starting lineup against the Saints, so Tomlin and Giles are likely to be in the XI.
As for Southampton, Hasenhuttl is expected to again field a couple of different lineups in South Wales as he looks to give as many players minutes as possible.
Romain Perraud is the only new arrival at St Mary's this summer so far, and the former Brest full-back is in line for a start here.
Cardiff City possible starting lineup:
Smithies; Ng, Flint, Nelson, Davies; Vaulks, Pack; Tomlin, Harris, Giles; Collins
Southampton possible starting lineup:
Forster; Walker-Peters, Bednarek, Salisu, Perraud; Romeu, Ward-Prowse; Walcott, Redmond; Tella, Ings
We say: Cardiff City 1-1 Southampton
Cardiff will have supporters in attendance for Tuesday's friendly in what is their penultimate run-out before the 2021-22 Championship season gets up and running.
McCarthy is still working out his best XI, which is also the case for Hasenhuttl, and we can see the sides playing out a well-fought draw in South Wales.