Colombian Montero struck either side of half-time to give his side a useful lead to protect when they travel to the Czech Republic for the return fixture.

Marcos Acuna clipped the top of the bar with a left-footed curler in the opening minutes but Jorge Jesus' side struggled to break down stubborn opponents for the majority of a low-key first half.

However, just as it seemed the game would be scoreless at the break, Sporting produced an eye-catching move to cut Plzen open.

Bryan Ruiz's chipped pass inside from the left touchline allowed the supporting Fabio Coentrao to spectacularly volley across to Montero, who controlled on his chest before steering the dropping ball beyond goalkeeper Ales Hruska.

The same player struck again just four minutes into the second half, shifting the ball onto his left foot inside the penalty area to curl a shot around Plzen captain Roman Hubnik and into the net.

Hruska had little chance with either goal but the keeper did make smart saves to stop Ruiz and then Bruno Fernandes increasing Sporting's advantage before the final whistle.

Jeremy Mathieu also failed to convert a late one-on-one opportunity but, despite Sebastian Coates and William Carvalho picking up bookings, ruling the pair out of the second leg, Sporting hold the upper hand at the halfway stage of the contest.