With five rounds remaining in the 2014 J-League season, Urawa top the table with 57 points, five ahead of Gamba, who lost their latest match 1-0 at Kashiwa Reysol.
It was a missed opportunity for Usami and co. with Urawa having been held to a scoreless draw at home on Wednesday by relegation-threatened Ventforet Kofu.
But despite that disappointment, Usami - who has been named J-League Player of the Month for September - insisted Gamba believe the title is still up for grabs, especially as they will play Urawa in the penultimate round.
"All players of Gamba are conscious that we must fight now," Usami told the J-League's website.
"It has been continuing now, I think, that it is possible to catch the Urawa Reds."
Gamba have surged up the J-League table since the start of September, winning six games in a row before their defeat at Kashiwa.
But it will be tough for Kenta Hasegawa's men to bounce back this weekend as they host sixth-placed Tokyo, although if they can pick up three points they could conceivably reduce Urawa's advantage, as the leaders travel to Kashima Antlers.
Urawa have stuttered over the past four weeks, losing twice and winning just once, while also conceding six goals in that period.
But in a boost for Mihailo Petrovic's team, Kashima have been similarly inconsistent over the same period, losing to both Gamba and Kashiwa.
Kawasaki Frontale (51 points) will also look to take advantage of any slip-ups by Gamba or Urawa, when they travel to Ventforet Kofu.
On Wednesday, Kawasaki defeated Sagan Tosu to leapfrog both them and Kashima into third.
Both Tosu and Kashima have 50 points with the latter ahead on goal difference.
Tosu will host Albirex Niigata on Sunday.
In other fixtures, Cerezo Osaka - who sit second-bottom - will look to build on their midweek victory over last-placed Tokushima Vortis when they travel to Yokohama F Marinos.
Cerezo (29 points) are two points from safety with rivals Shimizu S-Pulse and Omiya Ardija in danger of dropping into the relegation zone if they lose to Sanfrecce Hiroshima and Vissel Kobe, respectively.
Vegalta Sendai will host Kashiwa and Nagoya Grampus will visit Tokushima.
