BERLIN, Aug. 29 (Xinhua) -- Mainz' left back Park Joo-ho joined Borussia Dortmund with immediate effect, the "BVB" announced on Saturday.

The 27-year-old Mainz defender agreed on a transfer to league rivals Dortmund after inking a contract until June 2018.

"Park Joo-ho is as a left back the ideal addition to our squad," Dortmund's sporting director Michael Zorc told the club's official homepage.

The South Korean international joined Mainz in July 2013 to score one goal in 44 appearances for the "Nuellfunenfer". The defender is since 2010 part of South Korea's national team where he made 26 caps ever since.

The "BVB" encounter Hertha Berlin at the third round of Bundesliga on Sunday.