Who are the heroes that carried MLS's final four to the conference finals?

The 2016 Major League Soccer playoffs are down to four teams vying for two spots in the MLS Cup final on Dec. 10.

Four teams, four unique paths to the conference finals; paths cleared by coaches and systems, but also by heroes. When soccer is of the knockout variety and the stakes are at their highest, every team needs a player or two who can step up and do what's necessary to secure a win.

Here are the heroes of the 2016 playoffs -- so far. With five games left in the postseason, we'll almost certainly have a new set of heroes to celebrate.

Seattle Sounders: Nelson Valdez and Nicolas Lodeiro

Nelson Valdez has taken plenty of criticism for underperforming his contract. The Paraguayan is earning designated player money from the Sounders, but over the course of his season and a half with Seattle, Valdez has put the ball in the net just once in regular-season play. He failed to score during the 2016 regular season in 24 appearances.

But Valdez has proven to be much more effective in the postseason. In the opening leg of the conference semifinals, Valdez scored the opener in Seattle's 3-0 victory. That goal was backed up by a pair of scores from Nicolas Lodeiro. The Uruguayan was a major part of the Sounders' late-season run to the playoffs, and he lived up to his reputation.

Montreal Impact: Ignacio Piatti and Matteo Mancosu

With all due respect to Sacha Kljestan, Bradley Wright-Phillips and David Villa, no single player is more valuable to his team in MLS than the Montreal Impact's Ignacio Piatti. If the playoffs played a role in the MVP voting, the Argentine attacker might even take away the prize from one of the three official finalists. The Impact stand at the precipice of an MLS Cup final appearance because of Piatti.

He started his brilliant playoff run in Washington, where he scored once and provided an assist to help Montreal storm out to a 4-0 lead in a knockout-round match they eventually won 4-2. He carried that form into the conference semis against the Red Bulls, scoring twice on the road at Red Bull Arena to put the series away.

He hasn't done it alone, however. Striker Matteo Mancosu helped spark the Didier Drogba controversy because of the trust he earned from head coach Mauro Biello. Mancosu has paid back his boss with an excellent postseason run. Mancosu scored twice in D.C., then set up the Impact in the conference semis with a blistering goal against the Red Bulls.

Toronto FC: Sebastian Giovinco and Jozy Altidore

The Toronto double act of Sebastian Giovinco and Jozy Altidore has clicked into high gear at the perfect time. The pair of high-priced forwards are earning their significant paychecks amid an unprecedented run for the original Canadian MLS franchise. After years of failure, TFC is heading into a clash with Montreal because of Giovinco's understanding with Altidore.

The Italian returned from an injury layoff just in time for the playoffs. He opened the scoring in Toronto's knockout-round win over the Philadelphia Union, then took apart New York City FC over the course of two legs, grabbing a hat trick in the Bronx. No one needs to be told that Giovinco is a dynamic force when he's healthy, but he chose to remove all doubt in the playoffs.

Altidore has been nearly as good. The U.S. man set up Giovinco's opener against Philadelphia, scored the first goal in Toronto against NYCFC, then set up Giovinco and scored in the 5-0 romp in the second leg at Yankee Stadium. Altidore's hold-up play and passing ability make him the most effective target man in the league, and with Giovinco able to score from nearly anywhere, the pair are more Batman and Batman than Batman and Robin.

Colorado Rapids: Shkelzen Gashi and Tim Howard

What Colorado lacks in scoring prowess, it more than makes up for in big moments.

"Big moment" is the best way to describe Shkelzen Gashi's goal against the Galaxy in the second leg of the conference semifinals in Commerce City. This season, the Rapids have found a way to score the necessary goal or two in order to make their defensive prowess stand up as a way to victory. Down a goal on aggregate against LA, Gashi let loose from 40 yards with a twisting rocket that proved enough to take the game to extra time -- and eventually, penalties.

Goalkeeper Tim Howard stood tall as the hero during penalties against LA, backing up an excellent display over the course of the previous 120 minutes. Howard made two saves in the penalty shootout to lead the Rapids to victory. Now, after suffering a groin strain in the U.S. loss to Mexico on Friday, Colorado may have to do without him.