Swedish international John Guidetti struck twice as Celta Vigo all but ended Cadiz's Copa del Rey lifeline with a 3-0 win in the first leg of their last-16 tie on Thursday. (Read more football stories here)
Cadiz only made it to the last 16 after Real Madrid were expelled from the competition for fielding an ineligible player in the previous round.
But their chances of reaching the quarter-finals look bleak as former Manchester City and Celtic striker Guidetti opened and rounded off the scoring with sharp finishes from close range either side of Jonny's deflected second just after half-time.
Las Palmas also look well set for the last eight thanks to Momo's stoppage time winner to edge a five-goal thriller 3-2 at nine-man Eibar.
Aythami Artiles and Wakaso Mubarak cancelled out goals from Izet Hajrovic and Saul Berjon before late red cards for Hajrovic and Gonzalo Escalante turned the match decisively in Las Palmas' favour.
Holders and competition favourites Barcelona eased past local rivals Espanyol 4-1 in a bad-tempered encounter that saw the visitors have two men sent off on Wednesday.
There were also first-leg wins for Gary Neville's Valencia, Sevilla and Athletic Bilbao.
However, La Liga leaders Atletico Madrid have work to do in next week's second legs after being held 1-1 away at Rayo Vallecano.