The first MLS Rivalry Week of the 2017 season is upon us, and it's full of contentious clashes. Ready ... FIGHT!

Seattle vs. Portland When it comes to rivalries in MLS, there is none better than the Seattle Sounders and Portland Timbers. Although the pair didn't go head-to-head in Major League Soccer until 2011, their meetings on the pitch date back to 1975. With history and passion unparalleled in the league, the Cascadian rivals have also won the past two MLS Cups.

Red Bulls vs. NYCFC The New York Red Bulls didn't have a local derby to speak of until New York City FC joined the league in 2015. The two clubs have quickly cultivated a strong distaste for each other, a grudge that's keenly felt throughout New York and New Jersey, as demonstrated by an endless and entertaining barrage of tifos.

Houston vs. Dallas Since their last MLS Cup final appearance in 2012, the Houston Dynamo have taken home El Capitan (the 18th century howitzer awarded to each year's winner of the Texas derby) just once. FC Dallas has dominated the Lone Star state since, but with the Dynamo on course for their first playoff place in four years, the battle to light the cannon's fuse will be as fierce as ever.

D.C. vs. Philly D.C. United and the Philadelphia Union are two of five MLS clubs that can stake claim to the I-95 derby. Regardless of where these two clubs sit in the table -- and this season they're at the foot of the Eastern Conference -- it's always a street fight when United meet the Union.