Columbus Crew SC finally scored and got help from visiting D.C. United on two other goals for their first win, a 3-1 victory on Saturday.
Reigning MLS Cup champs Columbus (1-0-2, 5 points) had played consecutive scoreless draws to open defense of its championship but got a goal by Lucas Zelarayan in the 20th minute and a D.C. own goal by defender Frederic Brillant in the 63rd for a 2-0 lead.
D.C. (1-3-0, 3 points) has lost three straight.
Crew goalkeeper Eloy Room was working on his third straight shutout until Kamara, who entered in the 75th minute, scored his 56th MLS goal.
The Crew came right back with Zelarayan serving a cross to the near post that went off Alfaro.
Zelarayan scored the Crew's first goal of the season with a pinpoint free kick from 28 yards to the upper left corner. He was fouled by Yamil Asad to set up the restart.
The 2020 MLS Cup MVP scored his seventh regular season goal in his second season.
His score was the first shot on goal for the Crew, which had zero on target in the previous match vs. CF Montreal.
While the shots on goal for D.C. and the Crew were equal at one in the first half, Columbus was more dangerous in the final third in search of the elusive second goal with a 67.3 percent pass completion compared to 46.2 percent for D.C.
The Crew extended the lead to 2-0 when Luis Diaz sent an arcing ball from midfield to the chest of Pedro Santos on the left side of the box. Santos' blast hit goalkeeper Chris Seitz and caromed off Brillant, who was marking an incoming Gyasi Zardes.