Liverpool had fallen behind to Keane Lewis-Potter's first-half header and reached the interval facing a determined home side, although Brentford were reduced to ten men when Yehor Yarmoliuk was sent off in stoppage time.
Victor Muñoz equalised after the hour before Isak finished clinically eight minutes later to complete the turnaround. Brentford captain Vitaly Janelt was dismissed late on, leaving the hosts with nine players by the final whistle.
“Super-happy with the win,” Isak said. “It's a tough ground, it's a tough team to play, especially away from home. We knew it was going to be a fight, a bit of a scrappy game, and it's important to come out on top in these games.”
The Sweden international was pleased that Liverpool had collected the points, but did not suggest the result meant the team could relax.
“I think there's still lots to improve but we're taking steps and we're obviously grabbing points on the way, which is important. It's a tough place to come to, so three points is really good.”
Isak's goal arrived after he had spent much of the match waiting for an opportunity to make a decisive contribution. With Brentford defending deep after their first dismissal, space was limited, and the striker knew he had to make the most of the opening when it came.
“It was more about concentration because I didn't have too many chances,” he explained. “I was kind of waiting for my moment and that was the one. So, I just tried to get control of the ball and finish as quickly as possible. Luckily, it went in.”
The forward also recognised the challenge of breaking down a team protecting its penalty area with a numerical disadvantage.
“I think that's the way it is, especially in these games. When they go a man down, obviously they protect their goal a bit more, so there's not much space to play in. You've got to be ready for when the chance pops up.”
Liverpool's comeback offered another valuable result in a demanding away fixture, but Isak's assessment was measured rather than triumphant. He welcomed the points while recognising that the team's progress would ultimately depend on improving the performance as well as continuing to win.