The J. League season is only six games old, but already the early front-runners have hinted at their championship potential with a series of convincing performances.

Kawasaki Frontale lead the way as the only unbeaten team in the division, beating Sagan Tosu 1-0 on Sunday with a 94th-minute goal from Yoshito Okubo. Frontale also had an injury-time strike to thank for salvaging a 4-4 draw with Shonan Bellmare earlier in the season, and midfielder Yusuke Tasaka sees evidence of his team's mental fortitude in such late interventions.

"It's vital when you're going for the title that you can pick up three points even when you're not playing well," Tasaka said after Sunday's game. "I think we've become a tough team to beat."