The A's said they were selected by Iwakuma's current team, the Rakuten Golden Eagles, to hold exclusive Major League Baseball negotiation rights for the 29-year-old right-hander.
"The Oakland A's are excited to have had our bid for Hisashi Iwakuma accepted by the Rakuten Golden Eagles," the team said in a statement. "Out of respect for the posting process and for Mr. Iwakuma and his representative, we will not have any comment until the 30-day negotiation period comes to an end."
MLB.com reported the A's were vying with American League West rivals Texas and Seattle for the pitcher's services. The Golden Eagles of Japan's Pacific League are expected to get $16 million from the A's for the rights to Iwakuma.
The 10-year-veteran Japanese hurler racked up 21 win in 2008, and followed that with a 10-9 record last year. He was instrumental in Japan's 2009 victory in the World Baseball Classic, helping to pitch his homeland to the title, the Web site noted.