Darlington Nagbe is among three Portland players to miss Saturday’s match against league-leading FC Dallas. (Ted S. Warren/Associated Press)

This Saturday’s match between the MLS points leaders and reigning champions should be the marquee event of the weekend and create the type of buzz the league craves for a regular season affair. Instead, the FC Dallas-Portland Timbers showdown has lost much of its luster because MLS continues to insist on allowing games during the FIFA calendar.

Dallas has lost four potential starters to international duty. Portland will travel without three. The show will go on, reserves will fill voids and plenty of gifted players will take their usual places.

But at this pivotal point of the season — when the Supporters’ Shield and playoff races are at a fevered pitch, critical matches promise to sway the course of the campaign and some teams aim to maintain quality form while others are desperate to find it — MLS has again let down its clubs and supporters by stubbornly defying the sport’s annual agenda.

While most leagues around the world have stepped aside for countless World Cup qualifiers and other competitions, MLS will conduct eight matches over seven days.

The other games are not as tantalizing as Dallas vs. Portland but are, nonetheless, additional examples of how the league undercuts its own efforts of making the regular season matter (when 12 of 20 teams go to the playoffs) and cheats fans out of seeing teams at full strength.

(MLS) (MLS)

MLS has cited “scheduling challenges” for not stopping play during all FIFA windows, when clubs are required to release players to national teams. Over the years, the league has gotten better in respecting the calendar by arranging fewer matches and, when there is a conflict during the playoffs, going completely dark. It also has halted play during the group stage of the World Cup and, this summer, took a break for part of Copa America Centenario. (It should be noted, however, MLS’s commercial arm, Soccer United Marketing, had a business stake in Copa America.)

In all, more than 50 players from most of the 20 MLS clubs are affected this week and next. Not every team is in action, though. The San Jose Earthquakes, Seattle Sounders, Toronto FC, Sporting Kansas City and Houston Dynamo are off. Individual teams are given the option of skipping certain windows over the course of the the season.

Ironically, several marquee MLS players, such as David Villa and Didier Drogba, have retired from international duty and aren’t affected by the scheduling conflict. Other stars, such as Diego Valeri and Bradley Wright-Phillips, are not in the international mix.

Fourteen MLS players were named to the U.S. squad for two World Cup qualifiers, but six are from clubs that are off during this FIFA window.

The schedule will resume Thursday with New York City FC and D.C. United clashing at Yankee Stadium. NYCFC defender Ronald Matarrita will be in Haiti with the Costa Rican squad, while D.C.’s Steve Birnbaum will travel with the U.S. delegation to St. Vincent and the Grenadines. Both Costa Rica and the United States are seeking to secure passage to CONCACAF’s final round of 2018 World Cup qualifying.

NYC and D.C. have it easy.

On Saturday, the Vancouver Whitecaps, who are four points out of a playoff spot and stuck in a seven-game winless rut, will be without six players on international duty. Their guests, the New York Red Bulls, will have to compensate for the loss of two starters, including MLS assists leader Sacha Kljestan.

The Colorado Rapids will miss five players against the New England Revolution (one absence). The Columbus Crew, the 2015 MLS Cup runner-up which is on the brink of slipping out of postseason contention, lost four players for a trip to Los Angeles.

Both Colorado and Philadelphia, which visits Chicago, will carry on without their starting goalkeepers.

Technically, MLS scheduled only six matches during this FIFA window. But two others fall on Sept. 7, the day after the period closes. One involves Orlando City, which, in the race for the last Eastern Conference playoff berth, will not have its top two scorers, Cyle Larin and Kevin Molino (22 goals and 10 assists combined).

Opting out of playing in this FIFA window was fortuitous for San Jose and Seattle, which had six and five players summoned respectively. Toronto also got a break: Aside from three call-ups, the club announced Monday that 2015 MVP Sebastian Giovinco, whose 16 goals are tied for the league lead this year, will miss up to a month with quadriceps and adductor strains.

Injuries and suspensions are one thing; deliberately creating scheduling conflicts is quite another.

MLS ABSENCES DURING THIS FIFA WINDOW

Thursday

New York City FC vs. D.C. United

NYCFC: Ronald Matarrita (Costa Rica).

DCU: Steve Birnbaum (U.S.).

Saturday

Vancouver Whitecaps vs. New York Red Bulls

VAN: Kendall Waston (Costa Rica), Blas Perez (Panama), Giles Barnes (Jamaica), Christian Bolanos (Costa Rica), David Edgar (Canada), Marcel De Jong (Canada).

NY: Sacha Kljestan (U.S.), Kamar Lawrence (Jamaica).

New England Revolution vs. Colorado Rapids

NE: Je-Vaughn Watson (Jamaica).

COL: Tim Howard (U.S.), Jermaine Jones (U.S.), Shkelzen Gashi (Albania), Marco Pappa (Guatemala), Mekeil Williams (Trinidad and Tobago).

Chicago Fire vs. Philadelphia Union

CHI: David Accam (Ghana), David Arshakyan (Armenia).

PHL: Andre Blake (Jamaica), Alejandro Bedoya (U.S.).

FC Dallas vs. Portland Timbers

DAL: Kellyn Acosta (U.S.), Carlos Gruezo (Ecuador), Tesho Akindele (Canada), Maynor Figueroa (Honduras), Aubrey David (Trinidad and Tobago).

POR: Darlington Nagbe (U.S.), Alvas Powell (Jamaica), Jermaine Taylor (Jamaica).

Los Angeles Galaxy vs. Columbus Crew

LA: None. (Robbie Keane will play for Ireland on Wednesday but is expected back.)

COL: Justin Meram (Iraq), Harrison Afful (Ghana), Tony Tchani (Cameroon), Rodrigo Saravia (Guatemala).

Next Wednesday

Montreal Impact vs. Orlando City

MON: Maxime Crepeau (Canada), Johan Venegas (Costa Rica).

ORL: Cyle Larin (Canada), Kevin Molino (Trinidad and Tobago).

Real Salt Lake vs. Los Angeles Galaxy

RSL: Kyle Beckerman (U.S.), Omar Holness (Jamaica).

LA: None.