On Friday, the Professional Referee Organization (PRO) announced a lock out of the Professional Soccer Referees Association (PSRA) after the PSRA rejected a "no strike/no lockout" agreement with PRO. As a result, PRO said, replacement referees will take charge of MLS's opening-weekend matches.

“We have high confidence in the qualifications of our replacement officials and can ensure our fans, clubs and players that all games will be officiated at a professional standard that protects the integrity of our matches and the safety of our players,” said PRO general manager Peter Walton.

The eight head officials for the weekend MLS slate include four former or current FIFA referees, three former MLS officials, and a current NASL referee. Irish referee Alan Kelly (pictured above), who will be in the middle for Saturday's Seattle-Sporting KC match, previously refereed five FIFA World Cup qualifiers in Europe and three UEFA Champions League matches before moving to the United States in 2013. Abbey Okulaja, who will be in charge of Saturday's Vancouver-New York match, received the MLS Referee of the Year award in 2004.

These are the replacement officials assigned to MLS's opening weekend matches (head official listed first, followed by assistant referees):

Seattle Sounders vs. Sporting KC, Saturday, 3 pm ET

Alan Kelly, former FIFA Ireland. Currently lives in the United States.

Dimitar Chadarav – MLS Reserve, NWSL

Kyle Longville – MLS Preseason

D.C. United vs. Columbus Crew, Saturday, 7 pm ET

Andres Pfefferkorn – NASL Referee, MLS Preseason

Yevgeniy Mednikov – USL PRO

Stefan McHardy – MLS Preseason

FC Dallas vs. Montreal Impact, Saturday, 7 pm ET

Jorge Luna – Former MLS official (4th)

Luis Guardia – Open Cup

Pedro Trejo – International, NASL

Vancouver Whitecaps vs New York Red Bulls, Saturday, 7:30 pm ET

Abbey Okulaja – Former MLS Referee

Brandon Major – MLS Preseason, MLS Reserve, Open Cup

Eric Weisbrod – USL PRO

Houston Dynamo vs. New England Revolution, Saturday, 8:30 pm ET

Ramon Hernandez – Former MLS Referee

Isreal Fernandez – MLS Preseason

Marcos de Oliveira – MLS Preseason, NASL

Portland Timbers vs. Philadelphia Union, Saturday, 10:30 pm ET

Ioannis Stavridis – Former FIFA Greece. Currently lives in the United States.

Caleb Mendez – MLS Preseason, NASL

Andrew Bigelow – NASL, Open Cup

LA Galaxy vs. Real Salt Lake, Saturday, 10:30 pm ET

Javier Santos – Current FIFA Puerto Rico

Jairo Morales – Current FIFA Puerto Rico

Jose Da Silva – MLS Preseason, NASL

Chivas USA vs. Chicago Fire, Sunday, 3 pm ET

William Anderson – Current FIFA Puerto Rico

Jair Morales – Current FIFA Puerto Rico

Jose da Silva – MLS Preseason, NASL