Shakhtar Donetsk and Porto were goalless as the referee brought the first half to a close in the Ukraine, with the visitors looking the most likely to break the deadlock.
Both sides were happy to keep possession inside their respective halves and get a feel for their opponents in the opening stages, though the Portuguese side seemed the keener to get into dangerous areas early on.
The visitors came close on 13 minutes when full-back Danilo combined well with Cristian Tello on the right before unleashing a shot from 25 yards, sending the ball just wide of the Shakhtar goal with goalkeeper Andriy Pyatov scrambling across his line.
Tello threatened again a few moments later, getting to the by-line and sliding a cross in that was cut out by the sliding Yaroslav Rakitskiy. Muted shouts for a handball from the travelling support went unnoticed by the officials.
The referee would point to the spot with 10 minutes of the half remaining, however. A counter-attack by Porto led to Yacine Brahimi skipping over a challenge from Oleksandr Kucher, who could not resist clipping the attacker's legs and giving away the penalty.
Brahimi dusted himself down and took the spot kick himself, but the Ukraine keeper read the shot well, diving to his right and pushing the ball clear of danger.
Porto would not be deterred, though, with Brahimi and Tello again threatening, though the latter wasted the last chance of the half after he got in behind the defence and dragged his shot wide.