Who's in, who's out? Permutations for final day of UCL opening round

Only 18 matches remain in the league phase of the Champions League - and only a few knockout berths are still up for grabs. theScore takes stock as we head into Matchday 8 today and approach the knockout stages.

What's at stake?

It's simple: The top eight seeds advance automatically to the round of 16, while the 16 teams that finish below them enter the playoff round. Clubs between 25th and 36th will be eliminated from Europe altogether and won't even get to play in the Europa League.

If two or more teams remain tied at the end of Wednesday's eighth and final matchday - when all 36 sides play at 3 p.m. ET - goal difference will break the deadlock. If the teams are tied on goal difference, UEFA will account for goals scored, then away goals scored, then wins, and, if necessary, away wins.

If teams are somehow level on away wins, UEFA will determine how many points their opponents collectively amassed and award berths to the teams that effectively faced more challenging opposition. UEFA will extend the calculation to goal difference and goals scored if necessary.

Disciplinary records would then come into play. If teams still remain tied, UEFA will use the highest club coefficient to determine which moves on.

Seeding is important as the higher you finish, the less likely you are to face a high performer in the knockout round. For example, the top two won't play against each other until the final, as they'll be on opposite sides of the bracket. The same goes for the teams that make the playoffs. Clubs ranked ninth to 16th will earn seeds and host the second leg of their two-legged ties. The higher seeds will be drawn against teams ranked 17th to 24th.

The playoff draw is Friday, and the matches will begin Feb. 11 and end the following week on Feb. 19. The draw for the round of 16 takes place Feb. 21, with play beginning March 4.

Who's in?

Liverpool and Barcelona are the only two teams to officially book their tickets to the round of 16 so far.

The 16 teams below them in the standings are guaranteed at least a playoff spot but will jockey for better positions Wednesday.

Liverpool have a perfect 7-0-0 record but haven't quite locked down the No. 1 spot. A loss to PSV Eindhoven on the final day and a win for Barcelona against Atalanta would allow the Blaugrana to leapfrog the Reds. Only six teams can catch Barcelona, meaning they'll finish no lower than eighth.

Arsenal and Inter were already guaranteed playoff berths before playing on Matchday 7 and virtually sealed their passage to the round of 16 with victories over Dinamo Zagreb and Sparta Prague.

Atletico Madrid need a point from their final match against Red Bull Salzburg to confirm their place in the round of 16.

AC Milan, winners of five straight in the Champions League, jumped from 12th to 6th on Matchday 7 by narrowly beating Girona. They close out the league phase with a trip to Dinamo Zagreb.

Atalanta's 5-0 clobbering of 33rd-placed Sturm Graz wasn't enough to guarantee them a place in the top eight. Like Atletico, they will, at worst, end up in the playoff round.

Bayer Leverkusen are one of six teams on 13 points but are holding onto the eighth and final automatic qualification spot due to their superior goal differential.

Monaco posted their first win in five matches in a 1-0 contest against Aston Villa on Matchday 7 to ensure they'll progress. Both sides could yet secure an automatic last-16 spot, but neither control their own fate, and are currently slated for the playoff round.

Lille, and Brest also gained entry to the playoffs despite losses to Atletico and Shakhtar Donetsk on Matchday 7.

Feyenoord shut out Bayern Munich 3-0 to put themselves in a good position to close out the league phase with 16 points. The Dutch side takes on second-last Slovan Bratislava on the final day.

Borussia Dortmund and Juventus are through despite setbacks last week. Dortmund sacked coach Nuri Sahin after a 2-1 defeat, while Juventus sputtered to their 16th draw of the season against Club Brugge.

Real Madrid and Celtic join Dortmund and Juventus on 12 points. Madrid improved their Champions League record to 4-0-3 with a commanding 5-1 victory over Salzburg, while Celtic needed a fluky own goal to take down bottom side Young Boys.

Twelve points is enough to reach the playoff round because the only teams that can catch them are the six sides occupying the final six qualification places. All of these clubs will be hoping to improve their standing on Matchday 8, though, as finishing anywhere from 15th to 18th would put them on a collision course with the likes of Liverpool and Barcelona in the last 16.

Who's on the cusp?

There are nine teams still looking to punch a ticket to the playoff round.

Paris Saint-Germain and Manchester City are somehow two of them.

PSG have the advantage over their money-spinning rivals thanks to their 4-2 comeback win over the Premier League champions in the marquee encounter of Matchday 7. City are now on a measly eight points in 25th and need a win over Club Brugge to have a chance of progressing. Pep Guardiola's men will be eliminated with anything other than a victory over the Belgian outfit.

Ten points is considered the rough threshold for qualification, according to The Analyst's Ali Tweedale, who ran 50,000 simulations in September to determine how many points a team would need to move on.

There are four teams currently on 10 points, including PSG and Stuttgart, who face each other on the final day. A tie would be enough for both to clinch in virtually every scenario. A tie would only prove fatal for Stuttgart if 26th-placed Zagreb somehow beat Milan by seven goals or more.

Shakhtar Donetsk haven't been mathematically eliminated but need a rare combination of results - a 3-0 win over Dortmund, a 3-0 loss for Stuttgart, and straight-up losses for both City and Zagreb - to go through.

Who's out?

Nine teams have already been eliminated, with three more set to follow them out of the competition.

RB Leipzig are the most surprising on the list. They had a brutal run of fixtures against some of the best teams in Europe, including Atletico Madrid, Juventus, Liverpool, and Inter but at least broke their losing streak with a 2-1 win over Sporting on Matchday 7.

Slovan Bratislava and Young Boys are the only two teams without a point thus far. Bratislava have conceded a league-high 24 goals, while Young Boys have scored a paltry three goals in six matches.

Sparta Prague and Girona had the faintest hopes entering last week's matches and were put of their misery with defeats to Inter and Milan.

Salzburg, Sturm Graz, Crvena Zvezda, and Bologna are also goners.

As it stands

Bound for round of 16

Bound for playoff round

Heading for elimination