The 24-year-old fullback for Major League Soccer's New York Red Bulls expertly curled a left-footed free kick around the Mexico wall and just under the crossbar to deliver Jamaica a stunner at the Rose Bowl.
The Reggae Boyz advanced to face the host United States in Wednesday's championship match at Santa Clara, California. The US squad beat Costa Rica 2-0 in a Saturday semi-final.
Despite sending most of their best players to Russia for the Confederations Cup, the Mexicans saw the dismal result as a reason for soul-searching and self-examination, acting manager Luis Pompilio Paez said.
"We have to make adjustments. We're determined to give out best. When we do not win, we all have to do self-criticism and reflections. This is a process and we all have to improve."
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It was only the third-ever victory for Jamaica over Mexico as the Reggae Boyz avenged a 3-1 loss to the Mexicans in the 2015 Gold Cup final after battling them to a goal-less draw earlier this month in the group stage.
"El Tri" trailed for the first time in the tournament when Lawrence chipped in the impressive shot from 25 meters out off a free kick set up by Hugo Ayala's foul on Jamaican substitute Michael Binns.
The seven-time champions pressured Jamaica to the finish but could not net the equalizer.
"We had the illusion of giving a victory to the Mexican fans," Paez said. "What we lacked was efficiency.
"Jamaica gave priority to the defensive. Things were missing to score goals. We look for all the sides, as it is necessary to look for the goals. The effort was made, we were efficient, but not effective to solve."
"We want to go to a World Cup and transcend," Paez said. "We are very close to going."
Jamaica goalkeeper Andre Blake was credited with five saves, among his most impressive a two-fisted stop in the 65th minute off a Mexico free kick by Jesus Gallardo, whose line drive rocket from just beyond the penalty area was knocked away and cleared by the Reggae Boyz backline.
Time and again, Jamaica's shut-down defensive unit denied Mexico, Rodolfo Pizarro coming away empty in the 75th minute wide of the far post and Blake thwarting a Gallardo header in the 81st minute.
The Jamaicans became the first Caribbean side to reach the North American regional tournament final when they upset the US squad 2-1 in the 2015 semi-finals and the rematch will give them a chance to make history as champions.
But this US squad is unbeaten in 13 matches since Bruce Arena took over as coach last year from the fired Jurgen Klinsmann.
The Americans seek a sixth Gold Cup title and their first since 2013.