In fact, the draw for the Champions League 16 has clearly stipulated three avoidance principles (many people only say that two are actually incorrect):
1 A team with the same ranking as the group match cannot be paired with the top 16 and eliminated (ranking avoidance).
2. The first and second place in the same group in the group match cannot be eliminated by 16 (avoidance in the same group).
3. Teams of the same Football Association cannot be paired/the top 0/6 of KLOC is eliminated (the same country avoids it).
In addition to the above three clear avoidance principles, the draw in the Champions League, like the draw in other competitions, has a hidden rule, which is to solve the deadlock in the draw as much as possible. What do you mean by drawing lots? You mentioned that when the sixth draw is Marseille, then Barcelona is drawn, then Arsenal behind you can't touch Manchester United or Chelsea (all three teams are from England) or Copenhagen (both teams are second in the group), which is the draw deadlock.
Of course, such a deadlock draw is definitely possible, so the hidden rule of a draw is to find a way to solve the deadlock, and the result of a draw cannot be cancelled (that is, Rome VS Miners, Milan VS Tottenham, Valencia VS Schalke 04, Inter Milan VS Bayern, Lyon VS Real Madrid cannot be changed if the sky falls).
In fact, after the fifth group draws lots, the remaining six teams draw lots very clearly. Arsenal can only draw Barcelona, Marseille can't draw Chelsea, and Copenhagen can't draw Barcelona. Therefore, we can know that if we smoke Arsenal first, we don't have to smoke any more, because we can only touch Barcelona. The rest of Marseille and Goben don't have to slap their opponents because Marseille can't touch Chelsea. The only thing the host has to do is to draw out the last two balls one by one, and prove that the signatures in the eight balls are indeed the second team names of the eight groups, and there is no cheating.
So if you see the process of drawing lots, when the host country won the sixth place and the second place was Arsenal, you won't draw lots. They will directly report that Arsenal's opponent is Barcelona, and when the seventh place is Marseille, they will directly report that the opponent is Manchester United, because Chelsea is already an opponent in the group stage. Copenhagen's final opponent is Chelsea.
Now let's take a vacation. You say Marseille is the sixth place, then the host will directly report that the opponent is Manchester United (Marseille can't touch Chelsea, Arsenal has locked in Barcelona), and there will be no more lottery. Arsenal or Copenhagen, whether seventh or eighth, will directly report that their opponents are Barcelona and Chelsea, and will not draw lots. By the same token, even if Copenhagen is the sixth place, the host will directly report that the opponent is Chelsea (Arsenal lock Barcelona, Marseille can't touch Chelsea).
Conclusion: Only when it is possible to choose a match will the lottery be drawn. When the remaining teams have only the possibility of matching, they will not draw lots and match directly. Just this time, Real Madrid was drawn in the 16 final draw, which became the only possibility of matching.
In view of the chaotic qualifying situation this year, it can also be understood that Arsenal is the second qualifying in Group H. If all avoidance principles are ignored, there can be 15 teams. However, according to the principle of ranking avoidance, the other seven teams that are also the second in the group will be eliminated, and the remaining eight teams will be the first. The principle of avoidance in the same group also removed the first miner in group H, and the remaining 7 groups were the first. Finally, the principle of avoiding the same country eliminated the number one Manchester United, Chelsea and Tottenham. So before the draw, it was determined that Arsenal had only four teams to choose from. If Bayern, Schalke, Real Madrid and Barcelona all arrange opponents before Arsenal draw, then there is definitely no opponent to play when Arsenal draw, so we should always pay attention to these problems when drawing lots. When the teams of Belarus, Saudi Arabia and Huang San drew lots, it was certain that Arsenal's opponent was Barcelona. Even if other teams are drawn instead of Arsenal, even if these teams can play against Barcelona under the principle of avoidance, they can't draw Barcelona. That is, the lottery ball with Barcelona note will not be put into the lottery cylinder. When Arsenal are drawn, only one goal from Barcelona will be put into the draw. In order to avoid a lottery deadlock.