Roma use a 3-4-3 formation with Nicolò Zaniolo and Diego Perotti in attack, while Porto have Moussa Marega and Tiquinho Soares in a 4-4-2.
The second leg in the Champions League Round of 16 kicks off at the Estadio Do Dragao at 20.00 GMT.
The Giallorossi won the first leg 2-1 at the Stadio Olimpico with a Zaniolo brace, but that late Adrian Lopez away goal leaves everything hanging in the balance.
Roma are fresh from a humiliating 3-0 Derby della Capitale defeat to rivals Lazio, but Porto also lost at home to Benfica at the weekend and fell off the top of the Liga NOS table.
Compared to the first leg, Porto have Jesus Corona (ban), Danilo Pereira and top scorer Marega back, but have revamped their usual 4-3-3 formation for a 4-4-2, allowing them to start Tiquinho Soares alongside Marega.
Mali international Marega scored in each of his last five Champions League appearances, equalling a club record set by Mario Jardel.
The only time this season he failed to find the net was the opening 1-1 draw with Schalke and he won the penalty, converted by Otavio.
Right-back Eder Militao was particularly impressive in Rome, but returns after being dropped for three games, as he was spotted out until 6am at a friend’s birthday party.
Roma are still without Cengiz Under, while Javier Pastore joined the absentee list with a recurring calf problem.
Coach Eusebio Di Francesco’s job is very much on the line here and he shocks everyone with a 3-4-3 formation.
Kostas Manolas is back in the starting XI after missing the Derby with a stomach bug, but Federico Fazio was so bad against Lazio that he has been sent to the stands, not even on the bench.
Juan Jesus steps in with former Porto centre-back Ivan Marcano.
Rick Karsdorp and Aleksandar Kolarov become attacking wing-backs, with Zaniolo and Perotti supporting Edin Dzeko.
Roma have not kept a Champions League clean sheet on their travels for precisely 12 years, since a 2-0 result at Olympique Lyonnais on March 6, 2007.
That was followed by 74 goals conceded in 31 games, including the preliminary rounds.
The Lupi have lost six of their last eight away games in Europe, drawing one and beating CSKA Moscow 2-1.
Porto: Casillas; Militao, Felipe, Pepe, Telles; Otavio, Danilo Pereira, Herrera, Jesus Corona; Marega, Soares
Porto bench: Vana, Maxi Pereira, Hernani, Brahimi, Oliver Torres, Adrian Lopez, Fernando
Roma: Olsen; Juan Jesus, Manolas, Marcano; Karsdorp, Nzonzi, De Rossi, Kolarov; Zaniolo, Dzeko, Perotti
Roma bench: Fuzato, Mirante, Santon, Florenzi, Cristante, Pellegrini, Schick, El Shaarawy
Ref: Cüneyt Çakır (TUR)
Watch Serie A live in the UK on Premier Sports for just £9.99 per month including live LaLiga, Eredivisie, Scottish Cup Football and more. Visit: https://www.premiersports.com/subscribenow