Celta Vigo scored twice in injury time to secure a 2-0 win at Espanyol.Giuseppe Rossi chipped a delightful finish in off the crossbar to give the visitors the lead, and there was still time left for Pione Sisto to charge the length of the pitch through a tired Espanyol defence and drill the ball low into the bottom corner.Espanyol manager Quique Sanchez Flores had guided his new team to a first victory of the season when they won away at Osasuna on Thursday, but they lacked a clinical edge when back at RCDE Stadium.Leo Baptistao should have put Espanyol ahead on 25 minutes after being played clear down the centre by Pape Diop, but the Brazilian forward shot straight at goalkeeper Sergio Alvarez.With 20 minutes left, Espanyol went close again when Gerard Moreno's shot was blocked and, from the corner, defender David Lopez saw his effort hacked off the line.The visitors, though, snatched all three points in stoppage time.Italian forward Rossi, on loan from Fiorentina, lofted an angled through ball from Gustavo Cabral over the advancing goalkeeper before Danish midfielder Sisto scored his brilliant solo effort, taking possession in his own half on the left and cutting back inside to power forward.Celta Vigo recorded their second win of the week to climb up into 11th place, while Espanyol drop into the bottom three following a third LaLiga defeat.