Save for a Mathias Pereira Lage shot that flew comfortably over the bar, there was nothing to separate this Europe-chasing duo in the opening quarter-hour.
But that all changed when VAR officials spotted a handball by Lacazette from a Brest corner, leading referee Benoît Millot to the monitor.
A moment’s consultation was all he needed to award Brest a penalty, which Kenny Lala side-footed high into the top-right corner to make it 14 conversions from 14 across his whole club career, as Lucas Perri dived the wrong way.
After Ludovic Ajorque fired past the far post from an angle barely a minute later, Lyon duly rallied.
Lacazette soon made amends with a well-timed run and a deft shot into the far corner of the Brest net, after a series of passes on the edge of the visitors’ box allowed Rayan Cherki to play a killer through-ball to the veteran marksman.
Thiago Almada should then have completed the turnaround, rushing on to meet Cherki’s ball inside the box, but he could only skew wide.
That said, Lyon were also fortunate to go in level at the break, with Abdullah Sima heading just over the bar. The game was thus finely poised, and the first real chance of the second half fell to Lacazette, who made a promising run into the box but was prevented from firing the correct side of the near post from an angle due to pressure from two Brest defenders.
Those same defenders were indebted to Marco Bizot moments later though, as a stooping Georges Mikautadze header forced him into a diving save.
Brest’s best hope of finally getting a maiden Ligue 1 away win at Lyon after a dozen failed attempts seemed to lie with Sima. And his lung-bursting run down the left just prior to the hour mark was a warning, given that he beat Clinton Mata for pace and was only prevented from getting a shot on goal by Tanner Tessmann’s sliding challenge.
With 82’ on the clock, a hero needed to step up, and just as Brest were hoping to bed in for a point, a ball from Cherki on the right flank found its way into the box for Lacazette to guide it home for his fourth matchwinner of the season.
The victory means that Lyon are now just four points off fourth-placed AS Monaco. Brest, meanwhile - having seen two penalty appeals for handball against Lyon turned down in injury time - now trail their still sixth-placed hosts by a concerning six-point margin, meaning that their hopes of a European encore in 2025/26 are now in significant jeopardy.
Flashscore Man of the Match: Rayan Cherki (Olympique Lyonnais)