Juve's Champions League hopes are no longer in their hands as they head for 11th-placed Bologna needing a win and hoping rivals Napoli and AC Milan slip up.
New champions Inter Milan have booked their spot in Europe's elite club competition, with second-placed Atalanta guaranteed a top-four place by virtue of their better head-to-head record over Juventus.
AC Milan and Napoli are both on 76 points, the former holding the best head-to-head record of the pair, while Juventus are one point adrift in fifth.
"The financial incentive for the clubs is plain to see, with a multi-billion dollar package at the heart of the scheme, albeit it would forever break the integrity of the club game," said Neil Wilson, chief market analyst at Markets.com.
Coach Andrea Pirlo said the 36-year-old Portuguese striker, the top scorer in Serie A this season with 25 goals, would rest to avoid risking a more serious injury.
Zlatan Ibrahimovic's AC Milan need to improve their home form to keep in the running for a first 'Scudetto' since 2011, having not won any of their last five games in all competitions at the San Siro.
The jury is still out on rookie coach Andrea Pirlo, with Juve also 10 points behind leaders Inter Milan in the Serie A title race ahead of Sunday's trip to Cagliari.
They do have a game in hand on Inter, which is against Napoli next Wednesday, and nothing other than two victories in those matches will do following Tuesday's disappointing showing against 10-man Porto.
Conceicao was part of the last Porto side to win the Champions League in 2004 under Jose Mourinho and masterminded their most significant win in the competition since then.
The feat came 17 years to the day when Porto knocked out Manchester United and Mourinho announced himself to the world with his iconic celebration on the Old Trafford touchline.
UEFA has proposed a major change to the Champions League from 2024 with 36 rather than 32 teams and an overhaul of the group stage into a single table rather than the current groups of four clubs.
UEFA's initial proposal allowed for extra spots to be given for teams placed highest in their rankings, opening the way for the top leagues to have more than four clubs on a regular basis.
However, Chiesa pulled Juventus back into the tie following a Rabiot run down the right with a pull back for the Italian to finish off into the corner of the net.