There was only one try in the first half and that was scored right on the halftime hooter by Southland loose forward John Hardie, who went over from a lineout drive to give his side an 8-6 lead.
The rest of the opening 40 minutes was made up of plenty of endeavour but little accuracy, though the defence of both teams was impressive. There was plenty at stake for both, too, equal as they were on the table with 20 competition points before kick-off.
The switch was flicked as referee Richard Kelly began the second half, Southland second-five Willis Halaholo scoring from a lineout win but with the benefit of a forward pass from first-five Marty McKenzie. Hawkes Bay supporters would have been aggrieved given Magpies wing Trinity Spooner-Neera had his try ruled out thanks to a transfer from Zac Guildford which had a similar trajectory.
Halaholo's try gave his side a healthy lead but the Bay began to dominate thanks to Coman and O'Connor and the increasingly assured play of wing Guildford and first-five Ihaia West.
Both backs scored to put their side back in front - Guildford thanks to an Andrew Horrell assist and West down the left touchline thanks to his blinding pace.
A late Brian Milne run would have given his side hope of a bonus point but the movement died and with it his team's hopes of a final say.
No 8 Elliot Dixon was one of Southland's best.
Hawkes Bay 23 (Zac Guildford, Ihaia West tries; Ihaia West 3 pen, 2 cons)
Southland 15 (John Hardie, Willis Halaholo tries; Scott Eade pen, con)
Halftime: 6-8