I think the chances are still 50:50 because both teams have not performed too impressively throughout this season. Roma's defeat to Milan in the last match proved that their defense is still very fragile, perhaps both teams will score goals in this game. Before facing Roma, Porto will also face Sporting CP in the domestic league, which will drain most of their energy because if they lose, their position is threatened to be taken by SC Braga.
Porto will face the top of the standings in the domestic league today which in general will be very difficult to win even though the match takes place at their home ground. And Sporting CP also does not want to lose in today's match even though the team also has to keep some of its main players fit so they can go through an important match in the UCL play-off round. But for Roma I think the team only needs to deploy its best tactics when facing Porto in the Europa League play-off round because Porto can also surprise many people when playing outside its domestic league.