The visiting Tigres had the better of the chances in the first half, with André-Pierre Gignac and Eduardo Vargas trying their luck, but the universitarios didn’t really threaten William Yarbrough’s goal.
There were two controversial moments, in the 15th minute when Alexander Mejía appeared to foul Gignac in the box and then in the 38th when Aquivaldo Mosquera brought down Javier Aquino, but referee Diego Montaño Robles declined to call a penalty on either play.
In the second half, León brought on Álvaro Ramos at halftime and in the 58th minute he played in Mauro Boselli, whose right-footed shot beat Nahuel Guzmán to make it 1-0 for the hosts.
Gignac came close to tying it in the 61st minute, but he was denied by the crossbar.
Meanwhile, the goal had lifted León’s confidence and La Fiera were pressing for a second. In the 70th minute, Andrés Andrade had a chance that forced a good save out of Guzmán.
Then, in the 75th minute, Tigres found the equalizer. Jesús Dueñas found Eduardo Vargas all alone about 25 yards out, and he ran on to the ball and made it 1-1 with his shot from the semi-circle.
With the 1-1 draw, Saturday’s second leg will be a winner-takes-all affair. If the two teams draw again, a 0-0 or 1-1 result would advance Tigres, while a draw of 2-2 or higher would send León through on away goals.
León: William Yarbrough, Andrés Mosquera, Juan González, Iván Piris (Álvaro Ramos 45′), Fernando Navarro, Juan Cornejo, Alexander Mejía, José Rodríguez, Eliás Hernández, Andrés Andrade (Maximiliano Cerato 85′), Mauro Boselli.
Tigres: Nahuel Guzmán, Juninho, Hugo Ayala, Jorge Torres Nilo, Luis Rodríguez, Rafael Carioca (Larry Vázquez 67′), Jesús Dueñas, Javier Aquino, Jürgen Damm ( Víctor Sosa 76′), Eduardo Vargas, André-Pierre Gignac (Enner Valencia 81′).