Montreal (3-5-2) won consecutive games for the first time to extend its unbeaten streak to three. Donovan Ricketts made six saves, three in the first 27 minutes, for his second straight shutout.
Sporting (7-2-0) had its second straight shutout loss after a club-record 7-0 start and gave up more than one goal in a game for the first time this year. Kansas City hasn't scored in 205 minutes, since the 65th minute of a 3-1 win over Vancouver on April 18.
Bernier's 63rd-minute spot kick was set up when Aurelien Collin pulled down Lamar Neagle in the penalty area on a breakaway in the 62nd. Martins opened the scoring in the first half, taking a layoff pass from Justin Braun and driving a left-footed shot just inside the left post from 25 yards.