Led by a rampaging David Fifita, the Rabbitohs took a major step towards returning to the finals for the first time since 2022 with a workmanlike victory at Accor Stadium on Friday night.
But the Bulldogs' hopes of featuring in September are all but over.
Should North Queensland see off Parramatta on Saturday, Cameron Ciraldo's men will be four points adrift of the finals places with just three full rounds of the regular season left to play.
Canterbury take on St George Illawarra, Penrith and Brisbane to round out their campaign and will no doubt look back on this loss to Souths as a game that got away.
"Hope's not a strategy - all we can control is how we how we play next Saturday night," Ciraldo said.
"We offloaded the ball to the opposition four times when the scoreboard wasn't that far ahead of us … we're just slow learners."
Stephen Crichton, Jethro Rinakama, Lachlan Galvin and Jacob Preston were all either held up or stopped short of the line in the first half.
And as South Sydney, who moved up to sixth, pulled away in the second half, the Bulldogs didn't have the firepower to go with them.
The Rabbitohs withstood plenty of early pressure but struck in the 23rd minute when Fifita, who finished with 144m and six tackle busts, pounced on a Cody Walker grubberkick.
Walker was the conductor for their second as the Bunnies shifted from right to left, the veteran playmaker sending Tallis Duncan through a hole to set up Alex Johnston.
Souths led 10-0 at halftime after Preston was penalised for a double movement and they moved out of touching distance from the restart.
Dogs hooker Bailey Hayward dropped the kick-off and Duncan crashed over on the left edge on the ensuing set.
"To come out and start like that after halftime just killed us," Ciraldo said.
Rinakama trudged off with a knee issue soon afterwards and the Bunnies pushed ahead further through winger Campbell Graham.
Missing a recognised goalkicker - Souths converted just one of their five tries - kept Canterbury alive though.
Enari Tuala finally scored on the hour mark but the Bulldogs' attack didn't have the spark to trouble Wayne Bennett's side, who completed the win with a well-deserved Matt Dufty try two minutes from fulltime.
"There's still three games to go and we've been in the eight all year, we're not there yet," said the Souths coach.
"They're learning how to win, these guys, and what works for them and what doesn't work and they applied it for 80 minutes."
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