The fable is that David beat Goliath by using speed and ingenuity to overcome the odds. The story ends soon after so we will never know what would happen if Goliath got a rematch two weeks later (because, yes, in the story David cut his head off, killing him) but in their second leg match, we will see if the Davidian Porto can make lightning strike twice or if the Italian Goliath of Juventus can live up to their oddsmakers.

The Bianconeri found themselves in a similar position last year and left it too little, too late: 1-0 down against Olympique Lyon in the first, they rallied 2-1 in the return leg, only to lose on away goals.

This time, though they play their home game at a 2-1 deficit, Federico Chiesa's 82nd minute lifeline got them an away goal that makes this practically a draw. Cristiano Ronaldo, who has developed a reputation as the comeback king of Turin, will be looking at this as his chance to be the hero and ensure his side makes it through into the quarterfinals.

To do that, he'll have to be much more active. He barely got a touch against Porto at the Estadio do Dragao; coach Sergio Conceicao knows his team are, by far, the smallest in the competition and therefore total underdogs in every aspect of the game – besides for one. He's drilled them on 4-4-2 fundamentals to within an inch of their lives and that back line, often in conjunction with the wide midfield, closed down Ronaldo every step of the way.

Due to the aforementioned Chiesa goal, Porto can't park the bus and treat the game at the Juventus Stadium in Italy tonight as a defensive showcase. Top strikers Mehdi Taremi and Sergio Oliveira will have to ensure they get at least one to ensure victory. Not only is the away goal rule now in their favor, the squad is so small that they simply don't have the legs to take this to extra time or penalties with confidence.

While Taremi did score in the first leg, it came barely 60 seconds in the game. Likewise, Moussa Marega's follow up came two minutes into the second half. Both goals were quick surprise attacks that came before Juventus could settle and get into the game. Once everything was flowing, the goals dried up.

The advantage on paper is entirely with Juventus so it's easy to overlook Porto. However, Porto didn't surprise Juventus once last game, they did it twice, and in doing so showed infinite potential for the type of upset only the Champions League can bring. Maybe they can do it again.