You have to play 45 games without grouping. Then: First, draw lots to decide the number 1- 10, and arrange it for 9 rounds, which should be:
First round, second round, third round, fourth round ... ninth round and so on, pay attention to 1.
1- 10 1-9 1-8 1-7
2-9 10-8 9-7 8-6
3-8 2-7 10-6 9-5
4-7 3-6 2-5 10-4
5-6 4-5 3-4 2-3