This season’s UEFA Champions League group stage reaches its climax on Tuesday and Wednesday, with the potential for great drama in five of the eight groups. There’s also the most star-studded clash of the group stage.

Every game Tuesday and Wednesday will be available online via CBS All Access and TUDN.com, with a few games televised on Univision, UniMas, TUDN and Galavision.

CBS will also have its popular whiparound show on CBS Sports Network, and Univision will have its whiparound show online. (Click here for the full game schedule.)

That will be true again Thursday for the final games of the Europa League group stage — including CBS’ first Europa League whiparound show on CBSSN. On all three days, each group’s games will be played simultaneously to heighten the drama.

In addition to all of that, on Wednesday night the U.S. men’s national team plays its last game of the year.

Before we get to the viewer’s guide, here’s what to know about tiebreakers. The first one is not goal difference, it’s head-to-head results in the group. The second tiebreaker is goal difference in head-to-head games, and the third is goals scored in head-to-head games. Overall goal difference is the sixth tiebreaker, believe it or not.

Group F: Zenit St. Petersburg vs. Borussia Dortmund, Lazio vs. Club Brugge

Tuesday, 12:55 p.m. (Zenit-Dortmund is on UniMas and TUDN; Lazio-Brugge is on Galavision)

Points: Dortmund 10, Lazio 9, Brugge 7, Zenit 1

Gio Reyna and Dortmund have clinched a round of 16 berth, but not first place yet. The Lazio-Brugge winner will advance (Lazio will with a tie), and the loser will go to the Europa League. Brugge, whose backup goalkeeper is American Ethan Horvath, can’t jump over Dortmund because Dortmund won both group contests.

» READ MORE: Christian Pulisic, Gio Reyna and Weston McKennie score goals on banner day for USMNT players in Europe

Group H: RB Leipzig vs. Manchester United, Paris Saint-Germain vs. Istanbul Baskasehir

Tuesday, 3 p.m. (Leipzig-Man United is on Galavision)

Points: Manchester United 9, PSG 9, Leipzig 9, Istanbul 3

You don’t have to be a soccer fan to know a three-way tie when you see it. Paris’ 3-1 win at Old Trafford last Wednesday set up the scenario everyone hoped for when this group was drawn. And not only that, Neymar’s 91st-minute goal to seal the game gave PSG the goal difference edge on United.

It’s all there for Tyler Adams’ Leipzig too, playing a win-and-advance game at home. And it has to be a win, not a tie, because United won their meeting in Manchester 5-0.

Group G: Barcelona vs. Juventus, Dynamo Kyiv vs. Ferencvaros

Tuesday, 3 p.m. (Barcelona-Juventus is on Univision and TUDN)

Points: Barcelona 15, Juventus 12, Dynamo 1, Ferencvaros 1

Barcelona won 2-0 at Juventus on Oct. 28, so barring a collapse it should hold on to first place. Given the Blaugrana’s many woes (and injuries) right now, there’s no guarantee. But really, this group isn’t about the standings, except for the battle for third place. It’s about Lionel Messi facing Cristiano Ronaldo in the Champions League for what’s likely one of the last times ever, between their advancing ages and Messi wanting to leave Barcelona.

And for American fans, there’s the added bonus of hoping to see Barcelona’s Sergino Dest and Konrad de la Fuente and Juventus’ Weston McKennie all on the field at the same time. It’s not out of the question. Dest and McKennie play regularly, and de la Fuente has come off the bench in Barcelona’s last two Champions League games.

Group D: Ajax vs. Atalanta, Midtjylland vs. Liverpool

Wednesday, 12:55 p.m. (Ajax-Atalanta is on UniMas and TUDN, Midtjylland-Liverpool is on Galavision)

Points: Liverpool 12, Atalanta 8, Ajax 7, Midtjylland 1

The big game here is Ajax-Atalanta, a head-to-head battle for second place. Both teams are brimming with attacking talent, highlighted by Ajax’s Dusan Tadic and Atalanta’s Papu Gomez and Duvan Zapata. The teams played to a 2-2 tie in Bergamo, Italy, on Oct. 27.

Group A: Red Bull Salzburg vs. Atletico Madrid, Bayern Munich vs. Lokomotiv Moscow

Wednesday, 3 p.m. (Salzburg-Atletico is on Galavision)

Points: Bayern 13, Atletico 6, Salzburg 4, Moscow 3

When this group was drawn, Salzburg knew it would need some luck to have a shot at making it out. Well, they got it, thanks to Atletico playing three straight ties: two with Lokomotiv, then last Tuesday at Bayern.

Atletico will be favored, thanks to its tenacious defense and star forwards Luis Suarez and Joao Felix. But if Salzburg can pull off the upset, it would be the biggest win of Princeton-bred manager Jesse Marsch’s career. It would also mean Brenden Aaronson gets to be in the Champions League immediately upon arriving from the Union.

» READ MORE: Brenden Aaronson dreams of success with the USMNT, and of maybe playing in the Champions League in a few weeks

Group B: Real Madrid vs. Borussia Monchengladbach, Inter Milan vs. Shakhtar Donetsk

Wednesday, 3 p.m. (Madrid-Monchengladbach is on UniMas and TUDN)

Points: Monchengladbach 8, Shakhtar 7, Real Madrid 7, Inter 5

This is the big one. Inter’s 3-2 win at Monchengladbach and Shakhtar’s 2-0 win over Madrid last Tuesday mean that all four teams enter their group finales alive to advance — and all but Borussia could also be eliminated entirely. Borussia’s worst possible finish would be third, if Real and Inter win.

The most pressure is on Madrid, of course, with its galaxy of stars and a record 13 European Cups in its trophy case. A loss at home to Monchengladbach combined with an Inter win over Shakhtar would put the Spanish superpower out of Europe entirely. The fireworks if that happens will be some spectacle.

United States vs. El Salvador

Wednesday, 7:30 p.m. (ESPNews, UniMas, TUDN)

The U.S. men’s team’s squad for its last game of the year has some intriguing young prospects from MLS, including Brenden Aaronson and Mark McKenzie. Other players to keep an eye on include Los Angeles Galaxy outside back Julian Araujo, Colorado Rapids midfielder Cole Bassett, Toronto FC forward Ayo Akinola, and Orlando City forwards Daryl Dike and Chris Mueller. And there’s one forward in from abroad: 20-year-old Sebastian Soto, who was allowed to come over from his Dutch club Telstar because he’s serving a red card suspension.

» READ MORE: Mark McKenzie’s USMNT callup a helpful distraction from Union transfer rumors

Europa League: Napoli vs. Real Sociedad; HNK Rijeka vs. AZ Alkmaar

Thursday, 12:55 p.m. (Napoli-Real is on UniMas)

Points: Napoli 10, Sociedad 8, Alkmaar 8, Rijeka 1

There isn’t much drama left in the Europa League group stage, but Group F has plenty. It’s no surprise, given the caliber of the teams involved: Napoli is an Italian power, Alkmaar has some great Dutch prospects, and Sociedad is surprisingly atop Spain’s La Liga.