One of the fiercest rivalries in Major League Soccer opens its latest chapter on Saturday night, as Real Salt Lake visits Sporting Kansas City at Children's Mercy Park. 

Fireworks are guaranteed when these two sides come together in any contest, whether it be the regular season, the U.S. Open Cup or the MLS Cup playoffs. 

The rivalry heated up once again in 2015, as Sporting KC moved over to the Western Conference following the arrival of New York City FC and Orlando City in the Eastern Conference. 

That led to three regular-season showdowns and an extra one in the semifinals of the U.S. Open Cup. RSL defended its home turf with a pair of 2-1 wins, while Sporting KC won the Open Cup semi and drew 0-0 inside its stadium. 

Saturday's matchup in Kansas City will have a little extra meaning for RSL if it comes out on top. The Claret and Cobalt have not won in Kansas City since 2009, and the visiting team in the rivalry has failed to win since July 2013, when Sporting KC was victorious at Rio Tinto Stadium thanks to a 97th-minute winner from Ike Opara. 

The clash at Children's Mercy Park will also have some early-season implications at the top of the Western Conference. RSL would love nothing more than to end Sporting KC's three-game winning streak and in the process pull within a point of its rival in the standings. 

In order to do that, RSL must avoid its fourth ejection of the season. Demar Phillips, Kyle Beckerman and Jamison Olave have all been delivered marching orders by referees over the first three weeks of the season. Beckerman and Olave both picked up red cards in Week 3's 2-2 draw with the Timbers, which means the two vital parts of the RSL setup will not be available for selection. 

Sporting KC will also be missing a key member of its midfield since Roger Espinoza was sent off in its Week 3 win over Toronto FC. Peter Vermes' team will be without one of its midfield enforcers, but at least it will have Soni Mustivar patrolling the space in front of the back four. 

As for who will be on the pitch on Saturday night, RSL's Joao Plata and Sporting KC's Dom Dwyer will face off in a battle of forwards. Plata earned Player of the Month honors for March thanks to his three goals and two assists. Dwyer hasn't been as productive in the numbers department, but he's had a massive influence on his side's attacking game plan. 

Given the form of the attackers on each side of the pitch and the history of the two clubs, we should be treated to another fiery clash between the pair of Western Conference rivals. 

In addition to the showdown at Children's Mercy Park, there are plenty of other intriguing matchups in Week 5. We'll have a look at them below. 

Week 5 Schedule

New York Red Bulls at New England Revolution (Friday, 7 p.m. ET, UniMas) 

Philadelphia Union at Chicago Fire (Saturday, 5 p.m. ET, MLS Live) 

Toronto FC at Colorado Rapids (Saturday, 8 p.m. ET, MLS Live) 

Real Salt Lake at Sporting Kansas City (Saturday, 8:30 p.m. ET, MLS Live) 

Columbus Crew at FC Dallas (Saturday, 9 p.m. ET, MLS Live) 

LA Galaxy at Vancouver Whitecaps (Saturday, 10 p.m. ET, MLS Live) 

Montreal Impact at Seattle Sounders (Saturday, 10 p.m. ET, MLS Live) 

D.C. United at San Jose Earthquakes (Saturday, 10:30 p.m. ET, MLS Live) 

Portland Timbers at Orlando City (Sunday, 8 p.m. ET, Fox Sports 1) 

Players to Watch

Clint Irwin, GK, Toronto FC 

Clint Irwin returns to Dick's Sporting Goods Park for the first time as an opposing player on Saturday. The 27-year-old was traded to Toronto FC by the Colorado Rapids in January to fill the Reds' void in between the pipes. 

Irwin comes back to Colorado alongside Drew Moor, who also joined the Reds from Colorado in the offseason. 

A strong performance in net from the American should help the Reds end their two-game winless run.

Harrison Afful, RB, Columbus Crew

The Columbus Crew come into Week 5 in need of a positive result after a rough March. However, that task will not be easy to accomplish since Gregg Berhalter and company head down to Toyota Stadium on Saturday to play FC Dallas. 

In order to leave Frisco, Texas, with points, Harrison Afful must contain the influence of Fabian Castillo on the left wing. If the Ghanian right back can stop Castillo, it will allow the Crew to commit multiple players to Mauro Diaz. 

If the focus remains on Diaz for 90 minutes, the Crew have a shot at stopping the owner of one goal and four assists. 

Gyasi Zardes, FW, L.A. Galaxy

Fresh off a two-assist showing for the United States men's national team on Tuesday, Gyasi Zardes will have to carry the load of the L.A. Galaxy attack against the Vancouver Whitecaps on Saturday. 

The United States international will be tasked with replacing Robbie Keane, who is out for four to six weeks after undergoing knee surgery, per the club's website. 

The good news for the Galaxy is Zardes bagged a brace in Week 3 against San Jose. If he banks off the momentum created from the last two weeks, the 24-year-old should have no problem scoring against Vancouver at home. 

Game of the Week

Portland Timbers at Orlando City

The final contest of the weekend at the Citrus Bowl pits two of the league's best forwards against each other. 

Portland's Fanendo Adi and Orlando City's Cyle Larin have been in great form to start the year, and they could easily extend their respective scoring runs in central Florida on Sunday. 

Adi scored his 10th career brace since joining the Timbers in 2014 in Week 3, while Larin has netted a strike in each of Orlando's first three matches. 

The other position worth watching on Sunday is defensive midfield. Portland's Diego Chara is one of the top destroyers in the league, while the underrated pair of Darwin Ceren and Cristian Higuita will challenge Diego Valeri every time he gets on the ball. 

Joe Tansey covers MLS for Bleacher Report. You can follow him on Twitter, @JTansey90. 

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