Juventus star Cristiano Ronaldo was stunned to be denied a penalty as Porto secured a surprise 2-1 win over the Italian champions in their Champions League last 16 first leg tie.
Juve were fighting back from a 2-0 deficit when Ronaldo, the competition's all-time top scorer, fell under a challenge in the Porto area in stoppage time but despite his hand flinging and incredulity, the appeals were waved away.
Goals from Mehdi Taremi and Moussa Marega propelled Porto to their first ever victory over Juventus.
On a night when little went the Italians' way, Federico Chiesa's late strike at least handed them a lifeline going into the return leg in Turin on March 9.
Taremi pounced on a sloppy back pass after 63 seconds to fire in the opener to rattle Juve, who failed to create any meaningful chances before halftime.
Things got worse for Andrea Pirlo’s side when Marega blasted in Porto’s second 19 seconds into the second half.
Juventus eventually mustered a response when Chiesa fired in a precious away goal with eight minutes remaining, but it was not enough to stop the 2004 European champions from celebrating their first win over the Italian club at the fifth attempt.
"Up to the 70th minute we blocked out Juve, we did a good job defensively," Porto coach Sergio Conceicao told Sky Sport Italia.
"We knew we could create problems for them with a high press, blocking their strong points, and they have many.
"On a strategic level it was a good game, but we’re only halfway."
Chiesa's strike ended Porto’s run of five consecutive clean sheets in the competition and left the tie wide open.
"Our approach made the game an uphill struggle," Chiesa said. "We conceded a goal after a few seconds and in the Champions League when you’re not fully focused they will punish you. The away goal will give us strength for the second leg."
