The international break has ended, and MLS's playoffs are finally here.

The new-look format, which creates a three-week sprint to determine the league's champion, kicks off Saturday with four single-elimination knockout matches, followed by another pair on Sunday.

The winners will advance to midweek matchups in the conference semifinals, with the conference finals taking place a week later prior to the Nov. 10 MLS Cup final at a site to be determined by the finalist with the best regular-season record.

Take a closer look at the six first-round matchups that will take place between Saturday and Sunday and the key question hanging over each one (all times Eastern):

No. 2 Atlanta United vs. No. 7 New England Revolution

Saturday, 1 p.m., Univision | Atlanta won 2-0, 3-1 in regular season

Key Question: How will Robinson's injury impact the champs?

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The defending champions are at home, are significantly better on paper than their opponents and should coast to the next round. But that's where the U.S. men's national team comes in.

Center back Miles Robinson, a finalist for MLS Defender of the Year and a key cog in the back for the Five Stripes, has been ruled out with a hamstring injury that was suffered during post-match sprints following the USA's Nations League win over Cuba. Robinson wasn't even supposed to be with the senior team, only tabbed when LAFC's Walker Zimmerman was forced to withdraw with a concussion. Frank de Boer ripped U.S. Soccer for how it handled Robinson, even saying that there had been discussions about taking it easy with his usage and how he was managed.

Now, Atlanta will be without its chief stopper in the back. Florentin Pogba or captain Michael Parkhurst could be called upon to fill the void, but Robinson's absence could give the Revs the opening they need to spring a shocker and move on despite being the worst side in the entire 14-team playoff field.

No. 2 Seattle Sounders vs. No. 7 FC Dallas

Saturday, 3:30 p.m., FS1 | Dallas won 2-1, they tied 0-0 in regular season

Key Question: Can Zdenek Ondrasek's hot streak continue?

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Zdenek Ondrasek had been one of the more disappointing signings of the season, until the Czech Republic forward turned it on in mid-August. Over a span of seven appearances down the stretch, Ondrasek scored all seven of his goals and added both of his assists to account for all of his personal stats this season. He padded that with his country, scoring a winner vs. England in Euro 2020 qualifying on his Czech Republic debut and adding two assists in a two-minute span in a subsequent friendly loss to Northern Ireland.

FC Dallas has always had the pieces to compete with anybody, but it's lacked the go-to goalscorer, with 18-year-old Jesus Ferreira leading the club with eight. Seattle's attack looks like it'll be at full throttle with Nicolas Lodeiro, Raul Ruidiaz and Jordan Morris all in form and fit to go. Might FCD have the firepower to match and make things interesting at CenturyLink Field?

No. 4 Toronto FC vs. No. 5 D.C. United

Saturday, 6 p.m., TUDN | Clubs tied both meetings in regular season

Key Question: How healthy is Jozy Altidore?

Kevin Sousa/USA Today Sports

Altidore suffered a thigh injury on Decision Day, and Toronto FC (and the U.S. men's national team, for that matter) is simply a less dynamic team without him. D.C. United didn't concede a goal in its last five games of the regular season, and while TFC has game-breaking talent in Alejandro Pozuelo, it could really benefit from a healthy Altidore to help tilt the scales.

D.C. will be playing to prolong Wayne Rooney's stay in MLS and has had plenty of goalscoring problems of its own, but the pressure is on Toronto, a team that is not far removed from being MLS's preeminent power but is in danger of becoming another also-ran if it can't put together a sustained playoff run after missing out altogether last season. A healthy Altidore, who was pivotal in the run to winning MLS Cup 2017, would go a long way toward making that happen.

No. 3 Real Salt Lake vs. No. 6 Portland Timbers

Saturday, 10 p.m., ESPNews | Portland won 2-1, 1-0 in regular season

Key Question: What are Diego Valeri's physical and mental states?

Jaime Valdez/USA Today Sports

Portland has been to two MLS Cup finals in the last four seasons, with its Argentine maestro being at the heart of it all. Now, he's battling a calf injury and is in the middle of a contract standoff, fully aware that he could have played his last game in Portland and could be facing his last game with the club. If he's good to go 90 minutes, that'll be huge. He scored the game-winning goals in both meetings with RSL this season.

With Brian Fernandez out indefinitely after entering the league's substance abuse and behavioral health program, the Timbers need an attacking fulcrum to step up, and who better than Valeri?

RSL, meanwhile, is playing to prolong Nick Rimando's career and would relish the possibility of Valeri either missing out or being at less than full strength. This is the same RSL team–well, minus Mike Petke–that went into LAFC and won a one-off match last season, so the hosts won't be easily dispatched regardless.

No. 3 Philadelphia Union vs. No. 6 New York Red Bulls

Sunday, 3 p.m., FS1 | Philadelphia won 3-2, New York won 2-0 in regular season

Key question: Whose playoff curse is stronger?

Kyle Terada/USA Today Sports

Neither of these clubs has enjoyed postseason success. The Union have never advanced in the playoffs in their history that dates back to 2010, while the Red Bulls have been consumed by falling short of expectations or shooting themselves in the foot despite winning three Supporters' Shields going back to 2013.

Both clubs limped to the finish line during the regular season, with the Union going 3-3-1 in their last seven games, while the Red Bulls went a paltry 2-4-1, failing to score in their last two games and falling out of contention to host a playoff match.

If there's any consolation for the Red Bulls, it's that they beat the Union (albeit at home) in their September matchup, but the club's attack has been so unspectacular, something that has not been helped by Bradley Wright-Phillips's form falling off a cliff as he became reduced to bit player. Manager Chris Armas is under pressure to deliver for the Red Bulls, but with the Union also desperate for postseason success and arguably in better shape thanks to the pending returns of Kacper Przybylko and Alejandro Bedoya, the hosts could be the ones to flip their narrative.

No. 4. Minnesota United vs. No. 5 LA Galaxy

Sunday, 8:30 p.m., ESPN | Galaxy won 3-2, they tied 0-0 in regular season

Key question: Can Zlatan dominate?

David Berding/USA Today Sports

Success for the LA Galaxy begins and ends with Zlatan Ibrahimovic. No club is as reliant on a superstar like the Galaxy are on Zlatan, not even after the addition of Cristian Pavon, which has added a dangerous new element to the team but hasn't really reduced the focus on Zlatan. Such is life with Ibra in the lineup, and it's a problem every team would likely welcome.

It's Ibrahimovic's first go-around in the MLS playoffs, and he's a player who lives for the big moments. He'll be going up against MLS Defender of the Year Ike Opara on a playing surface at Allianz Field that could be impacted by a college football game taking place on it Friday night.

All eyes are on a potential playoff edition of El Trafico, which would happen in the conference semifinals if the Galaxy can advance, but Minnesota has the home-field advantage, and the Galaxy's defense has proven to be quite porous all season. They'll need Ibrahimovic to be at his best to ensure that we all still have something to write about.