Porto survived the late dismissal of midfielder Fernando to ride out a 1-0 victory over Sevilla and take a big step towards reaching the semi-finals of the Europa League.
Two clubs famous for their attacking brands of football struggled to entertain at the Estadio do Dragao and the hosts needed a first-half diving header from defender Elaquim Mangala to edge the first leg.
Sevilla - UEFA Cup winners in 2006 and 2007 - were under par and could not put a move together to grab the away goal in the minutes that remained after Fernando saw red for arguing with the referee.
Jackson Martinez got Sevilla goalkeeper Beto working inside three minutes but it would be a cagey beginning to the first half.
Steven Defour dragged Porto out of their slumber with a speculative shot after 20 minutes and, three minutes before the opening goal, Ivan Rakitic forced a solid save from home goalkeeper Fabiano.
But as Ricardo Quaresma streaked down the left wing to rifle in an early cross in the 31st minute, Mangala made up the yards from the D to power the ball past Beto with his head.
Vicente Iborra and Defour then exchanged wayward strikes from distance before Silvestre Varela marked the end of the first period by warming Beto's palms with an effort from 20 yards.
Neither side could make inroads following the restart and it was not until the 67th minute that Martinez produced the first shot of an insipid second half.
His attempt from inside the Sevilla box sailed over the crossbar and, eight minutes later, Carlos Bacca was up the other end to test Fabiano's reflexes with a right-footed drive.
Coke's foul on substitute Juan Fernando Quintero gave Porto another opportunity to shoot at goal as the game entered its final 10 minutes but Quaresma's free-kick smashed into the defensive wall.
All of a sudden, Kevin Gameiro broke upfield with Fabiano looking stranded and, fearing the away goal, Fernando made the foul before being left as the last man.
He earned only a yellow card for the offence but promptly converted it into a second and therefore a red by protesting vigorously with referee Wolfgang Stark.
With only five minutes remaining, Sevilla were unable to test Fabiano again and must score at the Ramon Sanchez Pizjuan stadium next week to stay alive in the competition.