Former Liverpool legend Fowler admitted to relief when O’Donovan turned home a Wenzel-Halls cross in the 61st minute after a goalless first half.
From there he believed his team had got their just deserts for a confident display.
“If they go out and show that will and that desire every week, we have said before, we will beat a lot of teams but I think today was a point where we’ve probably gone out there and proved it,” Fowler said.
“We were good value for a win. I think from start to finish … I thought we were by far the better team.”
Brisbane started brightly with Jay O’Shea’s early free kick hitting the side netting but the Mariners nearly took the lead against the run of play in the 15th minute when Kim Eunsun’s shot smashed the crossbar.
Half-chances to Danny de Silva and Matt Simon came and went before a Roar surge in the final minutes of the opening half threatened to break the deadlock.
Wenzel-Halls, O’Donovan and Brad Inman either missed good opportunities or were denied by Mariners’ keeper Mark Birighitti and his defence before the break.
The pressure finally told for the hosts in the 61st minute when Wenzel-Halls broke free down the right and his cross was poked home by O’Donovan despite the attentions of Mariners’ defender Ziggy Gordon.
It’s the Irishman’s fifth goal of the season and seventh in six games against his former club.
Five minutes later, Neville doubled the lead when he rose above Giancarlo Gallifuoco to nod home O’Shea’s corner for his first goal for the Roar.
Mariners coach Alen Stajcic turned to youngsters Jordan Murray and Sam Silvera from the bench in an attempt to get back into the game.
Silvera was denied by Young after some slick work in the 81st minute but a frustrated Stajcic was shown a yellow card for dissent before the final whistle and admitted he’d felt his team had let themselves down.
“I thought we were very poor out of the blocks and didn’t really adjust to the game well,” Stajcic said. “They got a lot of momentum out of that early period but I thought as the half wore on we started get forward a little bit.
“That second half I thought was probably more shots and chances for us than them but, yeah, we didn’t execute and then they counter-attacked and got their one and again we’ve copped one off a corner.
“Very frustrating, very disappointed when I thought the game was there for the taking.”
Brisbane face defending champions Sydney FC at Kogarah next Saturday while the Mariners have a bye.