Real Madrid midfielder Dani Ceballos hopes he has avoided a serious setback after suffering a knee injury during Thursday's Copa del Rey win at Leganes.

Zinedine Zidane's ailing Spanish and European champions were once again short of their best form and had to wait until the 89th minute for Marco Asensio to give them a slender 1-0 advantage heading into next week's second leg.

Ceballos had left the field by that stage, replaced by Luka Modric midway through the second half, with his discomfort compounded by a collision with team-mate Lucas Vazquez.

The former Real Betis star has been restricted to just two LaLiga starts since joining Madrid during the close-season and has been linked with Liverpool and Inter this month, meaning any injury might have wider implications for the 21-year-old's future.

"I took a blow to my knee in the first half and then in the second I collided with Lucas," Ceballos told Madrid's official website.

"I hope to undergo tests [on Friday] and rule out anything serious."

Despite their struggles, Ceballos believes Madrid are in good shape for the second leg.

"In a knock-out tie it's crucial to keep a clean sheet and get an away goal," he said. "We've put the tie in our favour and we'll have to put it to bed at the Bernabeu.

"We thought the game was going to end 0-0, but Asensio popped up with a great goal and we take an advantage into the second leg.

"Leganes are having a good season and fighting for the European places. They played in a very compact style, they're a daring team and we struggled to beat them."

Ceballos added: "When the ball goes in, everything changes. We need to find more continuity in our play and remain patient."