Although Button topped the timesheet at the end of Friday's two 90-minute sessions at the Suzuka circuit, the Briton was naturally unsure as to his position as Friday times are never an indicator as to true pace.
But the 31-year-old in his McLaren would genuinely appear to be the man to beat in qualifying later on Saturday after comfortably finishing out in front in the final hour-long practice run.
Button finished with a lap of one minute 31.255secs for the 5.807km track, the fastest so far of the weekend, half a second clear of team-mate Lewis Hamilton.
You have to go back to Button's championship-winning year of 2009 and the Monaco Grand Prix, 45 races ago, for the last time he was on pole.
Champion-elect Sebastian Vettel, who requires a point to be crowned for a second successive year, was third quickest for the third time to leave Red Bull's run of 15 consecutive poles under threat.
Fernando Alonso in his Ferrari was the best of the rest, however a second down, with team-mate Felipe Massa sixth, the duo sandwiching Red Bull's Mark Webber in fifth.
The Mercedes pair of Michael Schumacher and Nico Rosberg both found themselves around 1.5secs adrift in seventh and eighth, with Vitaly Petrov in his Renault and Force India's Adrian Sutil completing the top 10, the latter two seconds down.
As for Paul di Resta, the Scot has so far struggled to keep pace with team-mate Sutil as he finished 0.6secs adrift of the German in 14th.
After 24 minutes Bruno Senna brought out the red flags by crashing into a barrier as he emerged out of Spoon Curve, a fast, sweeping left-hander.
The Brazilian made the simple mistake of running wide on the exit, getting on to the astroturf that lines the outside of the bend, and with no traction, was forced into an accident he could not avoid.
After hitting the tyre wall, Senna was spun round in his Renault as his car bounced back off it onto the track, breaking the front-left suspension.
The tethers did their job as the wheel remained attached, although via momentum Senna ran over it, lifting his car momentarily before coming to rest with the wheel perched on top of the car's nose.
Hispania's Vitantonio Liuzzi again found himself at the bottom of the timesheet following another failure with his car.
Liuzzi, who completed just four laps yesterday due to a water pressure issue, managed a further eight before being forced to pull off track 35 minutes into the session, finishing 9.8secs down.