By THOMAS FLOYD

A year ago, a meeting between FC Dallas and the Portland Timbers didn’t carry much weight in the MLS hierarchy. But when those clubs meet Saturday, they’ll do so as Western Conference front-runners.

Such is the parity-driven nature of MLS, which saw both teams retool in the offseason to great success. Now Dallas leads the West and Portland is just four points back heading into what should be an entertaining clash at Jeld-Wen Field, highlighting another light weekend of MLS action as World Cup qualifying carries on.

Elsewhere, Eastern Conference bottom-feeders D.C. United and Toronto FC face off in the nation’s capital; the Columbus Crew host the Montreal Impact; the San Jose Earthquakes move on without Frank Yallop against the Colorado Rapids; and the New England Revolution travel to face the Vancouver Whitecaps.

Here is a rundown of the Week 16 slate:

PORTLAND TIMBERS vs. FC DALLAS (Saturday, 5 p.m., ESPN)

The Timbers will put their 12-game unbeaten streak to the test against a Dallas team leading the race for the Supporters’ Shield. With Dallas’ David Ferreira and Portland’s Diego Valeri, two of the league’s top playmakers will roam the midfield in this one.

Both sides will be short-handed, as Portland winger Rodney Wallace is on Costa Rica national team duty and Dallas striker Blas Perez is with Panama.

D.C. UNITED vs. TORONTO FC (Saturday, 7 p.m., MLS Live/Direct Kick)

Neither team has won an MLS match in more than three months going into this meeting between the bottom two clubs in the Eastern Conference, which carry a combined 2-17-8 record.

Although United should be invigorated by their 3-1 win over Philadelphia in the U.S. Open Cup midweek, the team will have to make due against Toronto without midfielder Chris Pontius (concussion), defenders Ethan White (hip) and James Riley (adductor), and forward Carlos Ruiz (international duty).

COLUMBUS CREW vs. MONTREAL IMPACT (Saturday, 7:30 p.m., MLS Live/Univision Dep.)

Marco Di Vaio and the Impact will look to continue their league-best 2.17-points-per-game pace as they visit Columbus, which continues to struggle mightily against teams with winning records.

Both clubs will be depleted at centerback, with Alessandro Nesta suspended for Montreal and Glauber (knee) and Chad Marshall (hamstring) sidelined for Columbus.

COLORADO RAPIDS vs. SAN JOSE EARTHQUAKES (Saturday, 9 p.m., MLS Live)

With the season nearing its halfway point, Colorado and San Jose are both clubs on the outside looking in at the playoff picture looking to make a push. And the pressure is particularly heavy in San Jose, where reigning Coach of the Year Frank Yallop has parted ways with the club.

Interim coach Mark Watson’s task won’t be an easy one, as he will look to get a result at Colorado without the services of Honduran national team veterans Victor Bernardez and Marvin Chavez.

VANCOUVER WHITECAPS vs. NEW ENGLAND REVOLUTION (Saturday, 10 p.m., MLS Live)

Jay Heaps’ New England side that is unbeaten in five matches will try to maintain that fine form against the Whitecaps, who will be missing veteran centerback Andy O’Brien (hamstring).

Keep an eye on the flanks in this one, as the Revolution’s Saer Sene and Diego Fagundez try to cause trouble for the Whitecaps’ veteran fullbacks Lee Young-Pyo and Jordan Harvey.