Christian Ziege said it pained him to see Mesut Ozil not living up to his full potential.

Ozil, who started in Germany's opening 2018 FIFA World Cup match against Mexico on Sunday, was largely ineffective as the defending champions crashed to a shock 1-0 loss.

The Arsenal star was also involved in Mexico's goal as he failed to close down on Virving Lozano to score.

After the match, he was subject to criticism from fans and experts alike, something Ziege already saw too often.

"There have always been big discussions about him every game and big tournament. I remember we were also talking about him in 2014 when he was not playing that well," said the 72-cap former Germany international, who was in Malaysia as Astro SuperSport's World Cup pundit.

"People were saying about the way he played, moved and reacted to certain circumstances.

"There was another big discussion in Germany last week and everyone was saying how we have someone so talented but you just don't see [him using his talent].

"Sometimes you see it, sometimes you don't. Like in the Premier League, he could be playing well for Arsenal in one game and then you don't see him play well for the next three weeks.

"His body language and all are just not going his way.

"It hurts me to see a player of his quality not really being up for games and wanting the ball to do something with it."