A first-half goal from Andre-Pierre Gignac sealed a 1-0 victory for Tigres over Leon in the first leg of the Liga MX 2019 Clausura final on Thursday.
Gignac swept the ball in from close range in the 21st minute to draw level with Tomas Boy as Tigres' highest-ever goal-scorer with 104 goals.
Leon had finished the Clausura regular season in first place, but second-placed Tigres took the game to the opposition from the start and could've won by a wider margin with better decision-making in the final third.
Leon's first chance came in the 10th, when Vinicio Angulo steered a low cross from Angel Mena over the bar from close range.
The Clausura's top scorer Mena should've leveled in the first half when he found himself through on goal, but Nahuel Guzman smothered the ball before the Ecuadorian could get a shot away.
But Tigres also had chances in a game played without much emphasis on defense. Gignac went close just before half-time and substitute Enner Valencia shot over in the 73rd as Tigres racked up a total of 20 shots to Leon's nine.
"We need to stay calm, recover and heal the knocks," Leon coach Ignacio "Nacho" Ambriz said. "On Sunday, in our stadium and with our fans we have to play a good game to be able to finish this off."
He added: "It'd be worrying if we didn't go forward. Maybe we didn't create enough and we've gone two games without at goal, but there are 90 minutes left. We have to get stuck in more, there are a few things, but the last thing I have to do is despair and start experimenting, we have to play with our style, be courageous and have the determination to win the game."
The return leg will take place on Sunday in Estadio Leon, with the away goal rule not in place.
Leon is looking for its eighth title, while Tigres are currently on seven championships.