With the Panthers in range at 18-12 with 10 minutes to play Maloney peeled off his second 40-20 clearance of the season, Waterhouse infringed as the Warriors pressed during the resulting set of six and the five-eighth slotted a stress-relieving penalty before Vatuvei's 10th touchdown of the season confirmed the Warriors' place in the finals.
The Warriors can now determine their own destiny as the schedule helpfully pits them against the Dragons - who slumped to their fifth consecutive loss in Melbourne on Friday - in Wollongong on Sunday before the Cowboys travel to Mt Smart in the final round.
Six wins in their last seven matches suggests the Warriors can host a final the night the rugby World Cup kicks off across town on September 9 but Maloney was realistic ahead of assignments against the reigning premiers and Johnathan Thurston-inspired Cowboys.
Despite the attractive attacking capabilities of Johnson and Locke, Maloney, who slotted five goals from six attempts, described the win as "ugly".
"Those long range tries took a lot of heat off us and probably made the scoreline look a bit better than it was.
"We're happy obviously, we know for certain we'll be playing finals footy but we're not getting carried away," he said. "In terms of overall performance it's down a long way from what we need at this end of the season."
Maloney said complacency would not be an issue when they returned across the Tasman to WIN Stadium.
"To take Melbourne right down to the wire [the Storm won 8-6], they're doing all right. We don't want to be the team that plays them into form two weeks out from the semis."
The Dragons won 25-12 in Auckland back in round three so revenge would be perfectly timed.
"It means heaps," said Locke, of the Warriors climb from sixth to fourth.
They are on 30 points, one ahead of the Dragons and equal with the Cowboys but with a superior for and against.
Locke enhanced his reputation as one of the competition's most complete fullbacks - he put Johnson into the clear, produced a try-saving tackle on Waterhouse and then pouched a swirling kick before haring 60m to score after the halftime hooter. The Kiwi-in-waiting downplayed his impact.
"All the boys tried their best. All I wanted was to beat my opposition [Michael Jennings].
"I was pretty happy with chasing him down," he said.
Jennings was the victim of Locke's second try-saving lunge shortly after halftime. Jennings' return from a one-game ban, after turning up for training drunk, ended in frustration soon after when he withdrew with a shoulder injury.
It was an unhappy recall for the centre, who gifted Ben Matulino the Warriors' second try when he spilled a Maloney kick.
- NZPA
