Yuya Osako declared himself fit and ready for international week by opening his Bundesliga account in Cologne's 2-0 win at Stuttgart on Saturday.
"They controlled the game early on so I'm glad I could help us settle," Osako said. "I've been training well this week, and I went into the game feeling really good about myself."
Osako, a summer transfer from 1860 Munich, struck in the 22nd minute, scraping home a loose ball in the box to give the visitors the advantage.
Cologne went on to double the lead after 33 minutes through Anthony Ujah and held on for its first win of the season.
Osako has been called up by new Japan coach Javier Aguirre for his first games in charge on Sept. 5 and 9 against Uruguay and Venezuela, respectively.