Wolfsburg sporting director Klaus Allofs considers Cristiano Ronaldo a more selfish player than Lionel Messi, but acknowledged his mentality benefits Real Madrid.

Ronaldo and Messi have split the Ballon d'Or for the past eight years, with the Argentine star winning five to the Madrid talisman's three.

The Portuguese forward has scored six more club goals in all competitions than Messi this season, but it is Barca who top La Liga and face Sevilla in the Copa del Rey final in May.

Allofs says Ronaldo plays a more individual role compared to Messi, but his record in front of goal proves it works out well for Zinedine Zidane's side.

"I was asked the other day on German television about Messi and Cristiano. They are two incredible players," he told AS.

"In these cases, you have to see which players they have around them. With Messi, for instance, he has Luis Suarez.

"Ronaldo plays more for himself, but his magnificent statistics help the team get a result. That's why he scores so many."

Wolfsburg take on Madrid at the Santiago Bernabeu in the second leg of their Champions League quarter-final tie with a 2-0 aggregate advantage on Tuesday.

Allofs believes there could well be controversial officiating in the Spanish capital, though he hopes it is not the case.

"In the Bernabeu many things can happen. Things will happen that we cannot yet imagine, incorrect refereeing decisions, for example," he said.

"This is not certain, but it can happen and we must be prepared."