The 26-year-old playmaker has received criticism following a string of inconsistent performances for the Germany national team.
Mertesackler feels Ozil has been unfairly judged in England, while fans back home may not have watched enough to appreciate how well his teammate is doing.
“In Germany there are often only small parts of our games aired on TV or the opinions of English journalists are simply accepted,” Mertesackler told transfermarkt.de (via Goal).
Özil has hit the ground running during pre-season, Özil provided two assists and scored during Arsenal’s 6-0 victory over Lyon.
The 26-year-old featured in Arsenal’s 1-0 victory over Chelsea in the Community Shield yesterday.
Özil provided nine assists and five goals in 32 appearances for Arsenal in all competitions last season. The World Cup winner has been in good form since the turn of the year winning two Vitality Arsenal Player of the Month and a PFA Fans Player of the Month award.
Arsenal take on West Ham in their opening game of the 2015-16 season this weekend.