Holder Gamba Osaka set up an Emperor's Cup final showdown with Nagoya Grampus after beating feisty second-division champion Vegalta Sendai 2-1 on Tuesday.
Lucas gave Gamba a flying start when he pounced on an errant punch from Sendai goalkeeper Takuto Hayashi in the fourth minute, only to see the Tohoku side claw its way back just before the hour mark through Takayuki Nakahara at National Stadium.
But Lucas struck again with an opportunist's finish seven minutes later to send Gamba into a Jan. 1 meeting with Grampus, who came through a penalty shootout against Shimizu S-Pulse after a 1-1 draw earlier in the day.