Unlike the playoff round in the Europa League, where teams such as Villarreal generally play teams they've never heard of and are expected to win easily, the playoff round for the Champions League is a different matter. The draw for the fourth qualifying round (into which Villarreal will be placed) is AUGUST 5, with the two legged-knockout match to be played AUGUST 16/17 and AUGUST 23/24.
The Champions League has four qualifying rounds, but the first two only involve teams who are champions of their respective leagues, and in rounds three and four these champions are kept apart from the teams attempting to qualify who did not win their league.
Thus, the 32 teams qualifying for the Champions League will consist of:
22 teams which directly qualified for the group stage, of which 13 won their league title;
5 teams which won their league title but had to qualify for the group stage via the qualifying rounds for champions,
and 5 teams which neither won their league title nor qualified directly for the CL and made it through the qualifying rounds for non-champions. Villarreal is attempting to become one of these five. Got it?
So, to understand who our possible opponents might be, we first have to look at the third qualifying round for non-champions.
There will be 10 teams in this round, and we already know four of them: Benfica (17th in UEFA's team ranking, which determines the seedings), Dynamo Kyiv (30), FC Twente Enschede (49), and Rubin Kazan (62).
While the specific identities of the other six are unknown at present, we do know the league and league ranking they'll represent.
Swiss runnerup: either Basel (52) or Zurich (103)
Greece playoff champion: AEK Athens (64), PAOK (109), or Panathinaikos (32)
Belgian playoff champion: Genk (173) or Standard Liege (61)
Turkey runnerup: Fenerbahce (41) or Trabzonspor (135)
Danish runnerup: OB (104) or Brondby (157) are the two highest-rated possibilities
Romanian runnerup: Otelul Galati (201), Vaslui (156) or Timisoara (146)
Let's assume the highest-rated team wins their league (if not decided yet) and the next highest finishes in second place. As for the Belgian and Greek playoffs, they are incredibly convoluted, but let's assume the highest-rated team prevails there too. Then we would have the following groups of teams:
in the seeded pot in the unseeded pot
Benfica (17) Rubin Kazan (62)
Dinamo Kyiv (30) Zurich (103)
Panathinaikos (32) OB (104)
FC Twente (49) Trabzonspor (135)
Standard Liege (61) Timisoara (146)
A seeded team will be matched with an unseeded team via a blind draw. These two-legged ties take place in late July, and the five winners of those matches face the five teams that enter into the CL playoffs at this point. We know two of these for sure, and can guess at the other three:
Spain: Villarreal (19)
Germany: Bayern Munich (4)
Italy: Udinese (73) or Lazio (85)
France: Olympique Lyonnais (13), Olympique Marseille (24) or Paris St. Germain (38)
England: Arsenal (6) or Manchester City (42)
Again, these ten teams are seeded according to their coefficients. Let's assume Arsenal holds onto the automatic CL place in England, the seeded teams in the third qualifying round all win, and Lyon finishes in the CL qualifying position given to Ligue Un. Then the fourth round would have the following seeded and unseeded teams:
Bayern Munich (4) Panathinakos (32)
Olympique Lyonnais (13) Manchester City (42)
Benfica (17) FC Twente (49)
Villarreal (19) Standard Liege (61)
Dinamo Kyiv (30) Udinese (73) or Lazio (85)
If these indeed are the teams in the draw, it's interesting that Villarreal played Italian, Belgian, Dutch, and Greek teams in the Europa League last year, and have a 4-in-5 chance of drawing a team from one of those countries here--plus, of course, the chance to play FC Twente again.
The outcome of some leagues won't affect the overall analysis, but some could. Here are the ones to watch.
England: if Arsenal finish 4th instead of Manchester City (all else remaining the same), the Mancunians gain an automatic spot, Arsenal is seeded, Dinamo Kyiv unseeded, and hence a possible opponent for Villarreal.
France: if Marseille ends up in the Ligue Un qualification position, they would simply replace Lyon as a seeded team. But if Paris St. Germain gets the spot, Panathinakos would become seeded, and PSG unseeded. (but if Arsenal and PSG both get in, the Greek team would still be unseeded. Get it?)
Greece: The outcome of the Greek playoffs is critical since the other possible representatives are ranked so much lower than Panathanikos. AEK or PAOK might end up in the unseeded pot in the third round depending on results elsewhere, but Panathanikos would definitely be seeded.
Turkey: There is a large difference in coefficients between Fener and Trabzonspor. If Fener plays in the 3rd round they will definitely be seeded. If they win through, depending on other results they might be seeded, or might not, so could become another possible opponent for Villarreal.
We will know the results of the Belgian playoffs tomorrow, and the Turkey, Italy, England and Romania representatives will be determined this weekend. The Greek playoffs and Swiss league run until May 25, and the French and Danish leagues are the last to conclude, on May 29. I'll update the potential seedings after this weekend's results and again after the Greek and French results.
At that point we should be able to generate two possible groups of fourth-round seeds, depending on whether Benfica wins their third-round match or not.