Changing value of cell in one dataframe based on comparision another cell to another dataframe's cel

I've got two dataframes which looks like:

df1

col1            col2         col3
20              John         Positive
21              Kate         Negative
22              Nick         Another



df2

col1            col2         col3
21              message      white
22              text         black
20              nothing      orange,yellow
19              excel        blue

And I want to make them to look like:

df3

col1             col2         col3
20               John         orange,yellow
21               Kate         white
22               Nick         black

I want to change the value from df1 in col3 to value from df2 from col3 if the number from col1 of both dataframes matches. (In df2 in col1 I've got more values than in df1 col1, but it includes all numbers from df1 col1)

I've made solution which looks like:

for i in range(len(df2)):
    df1.loc[df1.col1 == df2.col1[i], ['col3']] = df2.col3[i]

And my solution is working, but it's really time consuming. I hope that using pandas I can improve my code. Do you have any idea how to do that?