Firstly Telles was booked for tripping Chelsea loanee Juan Cuadrado in the twenty-fifth minute and even before the ink was dry in the referee’s notebook the Brazilian full-back had scythed down Stephan Lichsteiner and was off for an early bath.
The home side fought a tight rearguard action for most of the game against a dominant Juve side but could do nothing to stop the Serie A champions from scoring twice.
Substitute Pjaca replaced Cuadrado after sixty-seven minutes and within minutes had given the visitors the lead.
Dani Alves needed even less time to double the advantage as he came on for Lichsteiner and struck just sixty seconds later, controlling Alex Sandro's cross before rifling home.
This was the first time that Porto had failed to have a shot on target in a Champions League knockout round since the game against Liverpool in 2005.
Juventus have now won thirteen of their last fifteen games and Porto face an uphill battle to overturn the two-goal deficit in Turin on the 14th March, where the home side are unbeaten since August 2015.