Felipe Gutierrez put the visiting side ahead inside 10 minutes and Johnny Russell doubled the lead just before the break for Sporting Kansas City.
Bastian Schweinsteiger set the stage for a comeback by setting up Aleksandar Katai for Chicago's first on 70 minutes, and the floodgates opened for the Fire. Two goals from Nemanja Nikolic followed, putting the home side in front in the 82nd.
But the fireworks were far from over.
Jimmy Medranda pounced on a rebound a minute later to pull Sporting back level, setting the stage for more Gutierrez heroics before the end of regular time, with the 27-year-old handing his side all three points in an engaging match.
Expansion franchise LAFC made their bow last week, stunning the Seattle Sounders away from home, and followed that up with another win on the road, crushing RSL thanks to Diego Rossi's brace and three assists, and a goal from Mexico international Carlos Vela .
Joao Plata put RSL ahead in the 20th minute despite having his penalty saved but the lead was brief in a one-sided affair at Rio Tinto Stadium.
Rossi, who netted the winning goal last week, equalized on the half-hour mark before Latif Blessing gave LAFC the lead three minutes later.
Benny Feilhaber joined in the fun two minutes after halftime with a routine finish from close range, while 20-year-old teammate Rossi added a fourth with nine minutes remaining.
Former Real Sociedad forward Vela completed the romp in the 86th minute when he sliced through RSL's defence and poked the ball past Nick Rimando as LAFC made it two wins from two matches.
After upstaging Tijuana in the opening leg of the CONCACAF Champions League quarterfinal tie during the week, the Red Bulls returned home to familiar surroundings and humbled the Timbers in their first MLS match of the season.
Carlos Rivas netted a late brace, while Bradley Wright-Phillips and 17-year-old Benjamin Mines also scored at Red Bull Arena, where the Timbers crashed to consecutive defeats.
Gyasi Zardes was at the double for the Columbus Crew , who preserved their perfect start to the season by seeing off the Montreal Impact 3-2 thanks to the United States international's 90th-minute penalty.
Elsewhere, the New England Revolution claimed a last-gasp 2-1 win against the Colorado Rapids, the Houston Dynamo lost 2-1 at home to Vancouver Whitecaps, who saw Kei Kamara reach the 100 goal mark , and Minnesota United went on the road and defeated Orlando City by the same scoreline.