Ivica Osim may have been pleased with the group effort in winning the Kirin Cup but the national team coach still has lingering doubts over the ability of certain players to toe the line as Japan prepares to defend its Asian Cup crown.

News photoJapan forward Naohiro Takahara shoots with an overhead kick during Tuesday's Kirin Cup match against Colombia at Saitama Stadium 2002. KYODO PHOTO

The 2-0 victory against Montenegro on Friday and scoreless draw against Colombia not only gave Osim his first piece of silverware as Japan coach but also plenty of selection headaches as he fine-tunes his squad ahead of the July 7-29 finals in Southeast Asia where a third straight Asian title is up for grabs.