Saturday's harsh defeat on the South Coast leaves us 11th in the 13-team standings, with one game remaining this season, when we face Aston Villa on Thursday evening (6:30pm BST kick-off) at Bodymoor Heath Training Ground.
Lorenz Hutchinson netted for the Foxes but it was the hosts who started quickest at Staplewood Training Ground, finding the net eight minutes in through Thierry Rohart-Brown.
By the end of the first half, Nicholas Oyekunle and Harry Gathercole had extended the lead to three goals before Leicester's strike a little over the hour mark.
However, not long after, Tinotenda Goremusandu gave the Saints a fourth to all-but confirm their win as they regained top spot in the league with 45 points. Goals from Gathercole and Sufianu Sillah Dibaga inside the last 10 minutes rounded off the scoreline.
With a final fixture against Villa this week, the Under-18s will hope to recover quickly in order to end on a high.
The details…
City: Donohue, Toko, Diallo, Gray, Khela; Akolbire (Boothe 85'), Donnelly (Omobolaji 46'), Aideed, Otchere (Owusu 62'), Daniels; Hutchinson.
Unused subs: Marson, Motsi.
Goal: Hutchinson 66'.