RIO DE JANEIRO, Feb. 15 (Xinhua) -- Neymar's father has described his son's critics as "vultures" and vowed the Paris Saint-Germain forward would come back stronger after his off-key performance against Real Madrid.

Despite his sublime Ligue 1 form, the Brazilian struggled to make an impact in the first leg of the Champions League round-of-16 tie in Spain on Wednesday, which the hosts won 3-1.

"In a war there are those who feed off victories and those who, like vultures, feed off the carcasses of the defeated," Neymar Sr said in an Instagram post.

"My son has been battling since he was a child, always fighting fair, always avoiding the vultures, always rising again stronger. In a war there are those who feed off victories and those who, like vultures, feed off the carcasses of the defeated."

The return match will be played in Paris on March 6 and Neymar Sr warned that the French club would not give up without a fight.

"We lost a battle but as for the war, we'll see, because it will last as long as we're on the field. And be sure...like a phoenix he will be reborn, prepared for the upcoming battle."

Some of the harshest criticism directed at Neymar after Wednesday's match came from former Brazil international forward Walter Casagrande, now a television commentator.

Casagrande accused the 26-year-old of selfishness and said Brazil was "creating a monster which some call a genius."

"He has already shown inappropriate behavior within a team," Casagrande told SporTV. "Against Real Madrid, he took a yellow in the first half and could have been sent off in the second.

"It would be disastrous if he acted like that at the World Cup. Neymar doesn't have the quality of Messi, [Diego] Maradona or Cristiano Ronaldo, who can win a match at any time."