Sporting took the lead six minutes of the second period as Diego Capel's impressive run down the left produced a low cross for Marat Izmailov to slot away.
They doubled their lead in the 64th minute through Emiliano Insua as the Argentine full-back's well struck free-kick went straight through the Metalist wall, and into goalkeeper Oleksandr Goryainov's bottom left corner of the goal.
The introduction of Marko Devic meant the visitors adopted a more direct style, and he had quite an impact.
In the dying stages of the match, the Ukraine international striker was brought down by Sporting goalkeeper Rui Patricio in the box, and captain Cleiton Xavier converted from the spot.
The goal will give some hope for Metalist going into the return fixture, which will be played next Thursday.
It was a quiet first half, as both sides cancelled each other out. Metalist, with their attacking instincts, could not find a way past the well-drilled Sporting defence.
Metalist had the better of the possession in the opening period, without threatening Patricio in the home side's goal. Taison and Xavier were limited to speculative efforts from distance, which were hit high and wide.
Indeed, it took until the 31st minute for the first shot on target. Sporting defender Daniel Carrico had a crack at goal from a fair distance out, but hit his well struck effort straight at Goryainov.
The only real chance of the opening 45 minutes came for Sporting, when Goryainov failed to deal with a floated free-kick from Matias Fernandez. The goalkeeper misjudged the cross, but Ricky van Wolfswinkel failed to get his shot on goal away cleanly.
The second half could not have been more different. Sporting were a team transformed in the opening stages, instantly pegging back their opponents. Izmailov and Joao Pereira looked bright, and it was the former who opened the scoring in the 51st minute.
The Russian was supplied by an inspired piece of play from the previously quiet Capel, firing his close range shot past Goryainov.
The home side continued to pile on the pressure, with Matias Fernandez forcing the Metalist goalkeeper to tip his free-kick over the bar.
The visitors nearly equalised when Cristaldo was played through on goal, but he hit his shot straight at Patricio.
Sporting increased their lead in the 64th minute through Insua's low struck free-kick. Goryainov looked livid with his wall, which jumped over the shot from the Argentine.
After recovering from the shock of conceding two goals within 13 minutes, Metalist finally began to threaten the home side's goal.
The introduction of Devic was crucial, and he nearly pulled one goal back in the 75th minute when the ball fell to him in the six-yard box, but the striker poked his shot straight at Patricio.
Taison and Jose Ernesto Sosa tried to add creativity to the Metalist attack, but it produced little end product.
Just when Sporting were looking like they were closing out the match, a long ball into Devic forced Patricio to concede a penalty, which was converted by Xavier. It was a cruel blow to the Sporting defence, who had been sound all game.
The late goal means the Ukrainians will still feel they have a chance in the second leg, but they will be missing their first choice central defensive pairing: Marco Torsiglieri and Papa Gueye both picked up yellow cards to rule them out of the match in Kharkiv next week.