The positive test comes a day before Madrid travel to Alaves in La Liga seeking to bounce back from an embarrassing midweek Copa del Rey exit.

"Real Madrid C.F. report that our coach Zinedine Zidane has tested positive for Covid-19," the club said in a statement.

Zidane already had to self-isolate this month after coming into contact with a person infected with the virus.

He tested negative at the time and was able to oversee the team.

After successive defeats in the Spanish Super Cup and Copa del Rey, the second a shock loss to third-tier Alcoyano, Zidane is again under pressure as Real Madrid try to reignite their La Liga title challenge away to Alaves.

Zidane's side are playing catch-up to Atletico Madrid after draws against struggling Elche and Osasuna, two of the league's bottom three, in recent weeks.

Alaves beat Madrid 2-1 in the capital in late November but have won just once in eight matches since, their slide into a relegation scrap costing coach Pablo Machin his job last week with former Spain international Abelardo Fernandez returning to take charge.

Real assistant coach David Bettoni said that Zidane was "fine" after his positive test, although "sad" not to be among the players.

"I spoke with the coach this morning and he is fine," said Bettoni.

"He was a little sad this morning not to be with us. He will not physically be with us, but we all know that he will be with us supporting.

"He will not be with us physically during tomorrow's game, but he will be with us to support the players, give his energy and help everyone."

Bettoni also played down talk of Zidane's future after their Copa del Rey embarrassment.

"You know the boss, he likes football, it's his passion. He is fortunate to coach this great club. In football it is a complicated time, but he is in good spirits," said Bettoni.

"I see him every morning with a smile, with joy, wanting to train. We want to carry on, we are fortunate to train at this club, so we enjoy them every day with our players."