Manchester United and Arsenal conclude their Europa League group stage campaigns on Thursday night with their exact position in their respective groups still undecided.
Erik ten Hag knows what is at stake for United as they travel to face Real Sociedad in a match that is a straight shootout for the all-important top spot in Group E.
Arsenal occupy first place in Group A going into their final game against FC Zurich at the Emirates Stadium.
Manchester United’s defeat to Real Sociedad on matchday one could still prove costly
Mikel Arteta’s Arsenal are better placed to win their group than their Premier League rivals
Both sides will be keen to win their groups, but why is top spot so important? And who could they face in the next round?
Here, Sportsmail takes you through United and Arsenal’s permutations, including who they could face if they fail to achieve their main target on Thursday night.
How do the tables look with one game to play?
United are second in the group with 12 points from their five matches so far, three behind Real Sociedad, who have a 100 per cent record. The two teams have already qualified for the knockout stages.
Real have the head-to-head advantage over United and also a better goal difference – +9 compared to +6.
Arsenal sit in top spot on 12 points, two clear of PSV in second. But, like their Premier League counterparts, they have a worse head-to-head record than their rivals.
What do Manchester United and Arsenal need to do to top their groups?
Nothing less than victory in San Sebastian by at least two clear goals will do for Ten Hag’s men.
Should United beat Real Sociedad, both teams will end level on 15 points. Under Europa League tie-break rules, final placings are decided on head-to-head record between the sides in question.
As the La Liga outfit overcame United 1-0 at Old Trafford in September, the Red Devils need to better that score in Spain to leapfrog Real into top spot.
If United win 2-1, 3-2 or even 4-3, the teams will be level on goal difference in their head-to-head record but the Spanish side will take first place by virtue of their superior goal difference across the six matches. Away goals in the two games between United and Real Sociedad do not count.
Arsenal are in pole position and will top their group if they beat FC Zurich on Thursday
A victory by two clear goals will ensure United have a better record over the two matches against Sociedad and would therefore see them top the group.
La Real are in the driving seat as they will go through as group winners if they avoid defeat or lose by a single goal.
Arsenal’s path to the top spot is a little more straightforward: win and it is theirs. All they have to do is better or match the result between PSV and Bodo/Glimt and they will safely progress to the last 16.
Should Mikel Arteta’s side slip-up on Thursday, they could finish second. If they draw with FC Zurich, and PSV overcome Bodo/Glimt, both the Gunners and PSV will end on 13 points.
Erik ten Hag knows exactly what is at stake when United travel to face Real Sociedad
But it will be PSV that takes first place in this scenario as the Dutch outfit have a better head-to-head record having beaten Arsenal 2-0 on matchday five, giving them an aggregate score of 2-1 across the two matches with Arteta’s men.
Why is winning the group so important?
The group winners progress directly to the last 16, while second-placed teams go to the last 32, which is an effective play-off against a side dropping out of the Champions League.
Taking top spot means two less matches and, in theory, a kinder run to the final.
United and Arsenal already have a packed schedule when domestic and European football resumes after the shutdown for the World Cup and could do without two extra games.
Who could Manchester United and Arsenal play if they don’t win the group?
In the play-off round, the eight teams who finish second in their Europa League group are seeded and drawn against one of the sides who have dropped out of the Champions League.
It is a potentially perilous path for United and Arsenal as Barcelona, Juventus, Ajax, Sevilla, Bayer Leverkusen, Sporting Lisbon, Red Bull Salzburg and Shakhtar Donetsk are their possible opponents.
Barcelona are among United and Arsenal’s possible opponents if they fail to win the group
Tough ties aplenty, there, but also plenty of intrigue – including the possibility of a swift return to Old Trafford for Juventus midfielder Paul Pogba.
And if they do?
United and Arsenal will head straight into the last 16 if they top the group.
There, they will be seeded and will be drawn against one of the eight play-off winners, with the second leg at home. They cannot play anyone from their own country.
Real Betis, Belgian side Union Saint-Gilloise, Ferencvaros and Freiburg are the teams to have guaranteed a place in the last 16 so far by virtue of winning their respective groups prior to the last matchday.
What are the dates for the next round?
The knockout round play-offs are scheduled for February 16 and 23, with the last 16 ties due to be held on March 9 and 16.
When is the play-off draw?
Monday, November 7 at 12pm GMT.
