Atalanta BC and Villarreal will lock horns in the Champions League on Wednesday night, with both teams battling for second position in Group F.

Villarreal are currently second in the section, one point clear of third-placed Atalanta, meaning that the home side will go through to the last-16 stage of the competition with a victory, but a draw or defeat would allow the Spanish outfit to finish second in the section behind Manchester United.

Atalanta have won one, drawn three and lost one of their five matches in Group F, which has left them in third position in the section on six points, but they would advance to the last-16 stage of the Champions League with a victory over the Yellow Submarine on Wednesday night.

The Italian giants were held to a 2-2 draw by Man United at the start of November before playing out a 3-3 draw with Young Boys towards the end of last month, with Luis Muriel's 88th-minute effort ensuring that the visitors would leave Switzerland with a point to show for their efforts.

Atalanta have been in excellent form in Serie A, winning each of their last five matches, including a 3-2 success over Napoli on Saturday, which has left them in fourth position in the table, four points behind leaders AC Milan.

Gian Piero Gasperini's side have reached the quarter-finals and round of 16 in the last two seasons of the Champions League, meaning that it would be somewhat of a surprise if the Italian team failed to finish in the top two, but they have struggled to show their best form in this season's competition.

A win on Wednesday would be enough to advance to the knockout round, though, and they would certainly be dangerous opponents in the round of 16 due to their quality in the forward areas.

Villarreal, meanwhile, will head to Italy knowing that they only need to avoid defeat to secure the position behind Man United in Group F, which has been a very competitive section.

The Yellow Submarine have won two, drawn one and lost two of their five matches in the group to collect seven points, with back-to-back victories over Young Boys placing them in a strong position in the group.

The 2-0 defeat to Man United on November 23 was a damaging result for Unai Emery's side, though, and they must now pick up a positive result in a very difficult match away to their in-form opponents.

Villarreal will enter the contest off the back of a 1-0 defeat at Sevilla in La Liga on Saturday, which has left them down in 13th position in La Liga, with the team winning just three of their 15 league games this term.

The La Liga club have twice reached the knockout round of the Champions League, making the semi-finals on their debut appearance in 2005-06 before reaching the quarter-finals three years later, but this is their first appearance in the group stage of this competition since 2011-12.

There is still plenty left to be decided in the final group-stage matchday of the 2021-22 UEFA Champions League, including several scenarios that could involve tiebreakers coming into play.

Keep the calculators stowed away. We've done all the work on the potential scenarios in which teams could finish tied on points in each group. 

Remember: Group winners will advance to the Champions League knockouts as seeded teams. They will be drawn against one of eight group runners-up in the Dec. 13 draw. Third-place finishers clinch a spot in the Europa League knockout playoffs.Below you'll find the official list of group-stage tiebreakers, followed by the specific tiebreaker scenarios for each group (Groups A-H).

Champions League group stage tiebreakers

According to the official 2021-22 Champions League competition rules, these are the tiebreakers used should two or more teams finish tied on points in the group-stage standings:          

1. points obtained in group matches played among teams in question
2. superior goal difference from group matches played among teams in question
3. goals scored in group matches played among teams in question
4. superior goal difference in all group matches
5. goals scored in all group matches
6. away goals scored in all group matches
7. wins in all group matches
8. away wins in all group matches
9. disciplinary points total based only on yellow and red cards
10. UEFA club coefficient

One twist to the tiebreaker rules: In the case three or more teams are deadlocked on points, tiebreakers Nos. 1-3 are first applied. If any teams are still tied after that process, then those same three tiebreakers are reapplied only to those remaining teams that are deadlocked before moving on to employ Nos. 4-10, if necessary.

Below are the tiebreaker scenarios for each group heading into final group-stage matchday on Dec. 8.

Group A tiebreakers

The only teams that could have finished tied on points entering the final day were RB Leipzig and Club Brugge. That scenario did not transpire after RB Leipzig beat Manchester City 2-1 and Club Brugge suffered a heavy defeat to PSG.

Those results left RB Leipzig with 7 points and Club Brugge in last place on 4 points. Leipzig claimed third place and will head into the Europa League knockout round playoffs

Group B tiebreakers

There were three teams within a single point heading into the final matchday and for that reason, there were four different scenarios in which the teams could have finished even on points. But those never came into play.

Porto went into the final day with a one-point lead on the other two, but managed to suffer a shock 3-1 home loss to last-place Atletico Madrid and watched the Spanish side overtake it for second place and the final knockout round berth in Group B.

AC Milan also blew it on the final day, losing at home to a Liverpool team that fielded several reserves. The Italians, currently in first place in Serie A, finished rock bottom of the group.

Group C tiebreakers

Borussia Dortmund (9 points) finished tied on points with Sporting CP (9 points), but Sporting went into the final day having already won the tiebreaker based on the head-to-head goal difference (second tiebreaker): +1 vs. Dortmund's -1 in their direct matchups. 

So it was already known that Sporting CP would finish ahead of Borussia Dortmund for second place no matter the results on the final day.

Group D tiebreakers

No teams could have finished tied on points in the Group D standings. Here's the final table:

Group E tiebreakers

There is one scenario that Barcelona and Benfica can finish even on points for second place, but it doesn't bode well for the Blaugrana.

Barcelona & Benfica

• Scenario: Barcelona (8 points), Benfica (8 points)

If Barcelona (7 points) ties its match at Bayern Munich, which would be considered a fantastic result under normal circumstances, it may not be enough to see it qualify for the Round of 16.

If Benfica (5 points) wins its match against last-place Dynamo Kyiv and finishes even with Barcelona on 8 points, it would claim second place based on the win and tie earned in the head-to-head matchups (first tiebreaker). 

Given the tiebreaker situation, Barcelona will need a win against one of the tournament favorites to guarantee a place in the knockouts.

Group F tiebreakers

There are three scenarios that could see teams tied on points in the Group F standings: 

Manchester United & Villarreal

• Scenario: Manchester United (10 points), Villarreal (10 points)

The reason that Manchester United has already clinched first place in the group because it wins the first tiebreaker against Villarreal based on its victories in both head-to-head matches (six total points).

Atalanta & Young Boys

• Scenario: Atalanta (7 points), Young Boys (7 points)

In case these two teams finished tied, Atalanta has already secured the tiebreaker over the Swiss side. The Italian side has a win and draw (four total points) in the two head-to-head matchups (first tiebreaker).

Villarreal & Young Boys

• Scenario: Villarreal (7 points), Young Boys (7 points)

Young Boys would also lose out to Villarreal on the head-to-head tiebreaker since the Spanish club has two victories in the head-to-head matchups (six total points).

Group G tiebreakers

It can get pretty wild in Group G with the potential of a three-way tie:

LOSC Lille & Wolfsburg

• Scenario: LOSC Lille (8 points), Wolfsburg (8 points)

This scenario would decide the second knockout-round berth in Group E, which would go to the German side. The only way this scenario materializes is with a Wolfsburg win against Lille on the final day. That win coupled with the 0-0 draw in France between these two teams would give Wolfsburg the tiebreaker on head-to-head points (4 vs. 1).

LOSC Lille, Wolfsburg & RB Salzburg

• Scenario: LOSC Lille (8 points), Wolfsburg (8 points), RB Salzburg (8 points)

This scenario would be a three-way tie atop the group, with only two teams advancing to the knockouts and one team settling for third place and a Europa League playoff berth.

The first tiebreaker (points in head-to-head matchups) would see the teams ranked this way: 1) Wolfsburg (7 points), 2) RB Salzburg (6 points), 3) Lille (4 points). That ranking would crown Wolfsburg as Group G winner, RB Salzburg as group runner-up and Lille as the third-place team advancing to the Europa League playoffs.

Sevilla & Wolfsburg

• Scenario: Sevilla (6 points), Wolfsburg (6 points)

Sevilla would claim this tiebreaker for third place and a Europa League playoff berth based on its win (2-0) and draw (1-1) in the two direct confrontations (4 points vs. Wolfsburg's 1 point).

Sevilla & LOSC Lille

• Scenario: Sevilla (9 points), LOSC Lille (9 points)

Lille would win this tiebreaker for first place in the group based on the win (2-1) and draw (0-0) secured against Sevilla in the head-to-head group matches (4 points vs. Sevilla's 1 point).

Group H tiebreakers

There are potential ties between the top two teams as well as the bottom two teams:

Chelsea & Juventus

• Scenario 1: Chelsea (12 points), Juventus (12 points)
• Scenario 2: Chelsea (13 points), Juventus (13 points)
• Scenario 3: Chelsea (15 points), Juventus (15 points)

Chelsea has already captured the tiebreaker against Juventus should both teams finish even on points after the sixth and final round of group matches are played.

Although both teams won a head-to-head match, Chelsea has the better goal differential in the direct confrontations: +3 for Chelsea vs. -3 for Juventus.

FC Zenit & Malmo FF

• Scenario: FC Zenit (4 points), Malmo FF (4 points)

If Zenit loses its final match and Malmo wins, the two teams would finish even on four points. But since Zenit has a win (4-0) and draw (1-1) in the two head-to-head matchups against Malmo, it wins the tiebreaker on points in direct meetings. 

For that reason, Zenit has already locked up third place and a spot in the Europa League knockout round playoffs.