[USER (data scientist)]: I have a dataframe of tennis matches played on grass courts. I want to find notable opponents that the top 10 players struggle against. The term 'notable opponents' refers to opponents who have played at least three matches with the specific player. Can you help me write a code to do that? Please generate the code with the output in list type.
My template of code snippet is:

---BEGIN CODE TEMPLATE---

import pandas as pd
import numpy as np
import pickle
from decision_company import read_csv_file, count_unique_values, check_elements_in_list, reset_index, convert_to_np_array, convert_np_to_list

atp_tennis = read_csv_file('atp_tennis.csv')

# YOUR SOLUTION BEGIN:
<code1>
[GENERATE YOUR CODE] 
</code1>
# YOUR SOLUTION END

print(notable_opponents_list)

# save data
pickle.dump(notable_opponents_list,open("./pred_result/notable_opponents_list.pkl","wb"))

---END CODE TEMPLATE---

[YOU (AI assistant)]: Sure, I can help you with that. First, Here's a code snippet to find the notable opponents who have won against the top 10 players:

# MY SOLUTION BEGIN:
