Lainez made the surprise start as a forward in a 3-5-2 formation before being subbed off for fellow Mexican Andres Guardado in the 75th minute.
Despite controlling possession early in the game, Real Betis were unlucky to go down in the scoreline midway through the first period when a giveaway in their own half led to Iker Muniain slotting home the 1-0.
Nonetheless, Lainez looked active for the “Verdiblancos” and even had a shot saved in the 35th minute.
Late in the second half, Betis were given a lifeline when Oscar de Marcos was sent off for a tackle on Sidnei. However, at the end they were unable to find the equalizer, as they went on to suffer their eighth defeat of the season
Next for Lainez and Guardado is a midweek Copa del Rey match against Espanyol, in a tie in which they are leveled 1-1 on aggregate heading into the Second Leg.