Here are the referee assignments for all the MLS matches in Week 12, per Professional Referees Organization (PRO).
SATURDAY, MAY 18
Toronto FC vs. Columbus Crew
BMO Field (5:00 pm ET)
REFEREE: JOSE CARLOS RIVERO
ASST 1: Chris Strickland
ASST 2: Marco Arruda
4TH: Hilario Grajeda
Vancouver Whitecaps vs. Portland Timbers
BC Place (7:00 pm ET)
REFEREE: MATTHEW FOERSTER
ASST 1: Jeff Hosking
ASST 2: Eric Proctor
4TH: Drew Fischer
Philadelphia Union vs. Chicago Fire
PPL Park (7:30 pm ET)
REFEREE: DAVE GANTAR
ASST 1: Eric Boria
ASST 2: Kevin Klinger
4TH: Kevin Terry Jr
Houston Dynamo vs. New England Revolution
BBVA Compass Stadium (8:30 pm ET)
REFEREE: EDVIN JURISEVIC
ASST 1: George Gansner
ASST 2: Frank Anderson
4TH: Armando Villarreal
San Jose Earthquakes vs. Colorado Rapids
Buck Shaw Stadium (10:30 pm ET)
REFEREE: RICARDO SALAZAR
ASST 1: Ian Anderson
ASST 2: Colin Arblaster
4TH: Allen Chapman
Seattle Sounders vs. FC Dallas
CenturyLink Field (10:30 pm ET)
REFEREE: MARK GEIGER
ASST 1: Joe Fletcher
ASST 2: Claudio Badea
4TH: Baldomero Toledo
SUNDAY, MAY 18
New York Red Bulls vs. Los Angeles Galaxy
Red Bull Arena (1:00 pm ET)
REFEREE: SILVIU PETRESCU
ASST 1: Peter Manikowski
ASST 2: Gregory Barkey
4TH: Jorge Gonzalez
D.C. United vs. Sporting Kansas City
RFK Stadium (5:00 pm ET)
REFEREE: JAIR MARRUFO
ASST 1: Paul Scott
ASST 2: Matthew Nelson
4TH: Daniel Fitzgerald
Chivas USA vs. Real Salt Lake
The Home Depot Center (10:30 pm ET)
REFEREE: SORIN STOICA
ASST 1: Corey E Rockwell
ASST 2: Fabio Tovar
4TH: Juan Guzman