Guatemala club Municipal defeated the Columbus Crew 2-1 on Wednesday in a Group B match of the CONCACAF Champions League.
Guillermo Ramirez scored in the 19th and 39th minutes to give Municipal a 2-0 lead. England's Andy Iro got one back for Columbus late in the first half.
The match was played in a downpour that made the field muddy with standing water, causing slipping in the second half.
The group's two quarterfinalists in the tournament for North American, Central American and Caribbean pro teams will be determined next month in the last two matches.
Santos faces Municipal and Columbus Crew plays Joe Public of Trinidad and Tobago.
Santos has 10 points followed by Crew (9) and Municipal (8). Joe Public has been eliminated.