Madrid, Dec 5 (IANS): Leganes benefited from a bit of luck and from a fine performance by goalkeeper Andriy Lunin to beat Rayo Vallecano 1-0 and advance to the Copa del Rey knockout stage.

The two capital sides started the game on Tuesday night at Madrid's Vallecas stadium and the first-half was marked by defensive errors.

But while Lunin was able to avoid disaster when a poor clearance by defender Kenneth Omeruo was about to cross the goal line, Rayo keeper Alberto could do nothing to stop a ball that deflected off teammate Emiliano Velazquez and into the net to put Leganes ahead 1-0 in the 16th minute, reports Efe news.

Toward the end of the half, Rayo's Bebe tested Lunin with a low shot before seeing the keeper stop him from the penalty spot.

Rayo dominated possession in the second half against a visiting squad content to wait for chances on the counter that turned out to be rare.

Lunin, who picked up a yellow card for time-wasting in the 70th minute, came up with key stops against Alvaro Medran and Sergio Moreno to preserve the fragile lead.