Bixente Lizarazu says Julian Draxler is thriving under less pressure at Paris Saint-Germain, and accused Barcelona of approaching their Champions League clash at Parc des Princes "like it was a friendly".

PSG registered a landmark 4-0 win over LaLiga champions Barca in the first leg of their round-of-16 tie on Tuesday, thanks to Angel Di Maria's brace, together with goals from Edinson Cavani and Draxler.

The 23-year-old attacking midfielder moved to PSG from Wolfsburg in January and is already impressing in Ligue 1, after struggling to meet the demanding expectations that accompanied being one of Germany's most promising talents in the Bundesliga.

"[Draxler] started very well, he's adapted himself very well, he's playing great games," Lizarazu told Omnisport at an event to mark his official appointment as a Bayern Munich ambassador.

"Against Barcelona, he was one of the best players. I think he has less pressure in France than in Germany, and I think he's had good and bad times in Wolfsburg and Schalke. 

"It's because he had a lot of pressure on his shoulders because he's a great rising star and the German media and the German fans expected a lot from him. 

"I feel like now that he is in Paris, he's playing with more freedom, with less pressure."

 Lizarazu did not hold back in dissecting Barca's demise in the French capital, labelling the effort produced by Luis Enrique's previously all-conquering team "terrible". 

"PSG played very well, Barcelona played very bad," he said.

"Usually, Barca doesn't play at such a terrible level, so this is why there was this difference; usually the difference is not that big. 

"But PSG started the game with the intensity and the aggressiveness needed for a Champions League, whereas Barca played like it was a friendly game."