Creating an if statement to compare column values in a dataframe and replace it with another one?

I currently have a dataframe of football results that goes something like this:

year	home_team	away_team	home_score	away_score	winner	penalty_winner
1872	Scotland	England	0	0	Draw	NaN
1956	England	France	1	1	Draw	NaN
1976	France	England	4	0	France	NaN
1999	Germany	Portugal	1	1	Draw	Germany
2021	England	Italy	0	0	Draw	Italy

What I want to do is replace the "Draw" values in the "winner" column with the values in the "penalty_winner" column only if the values are not "NaN".

I tried something like this:

if merged_international_results_df.loc[merged_international_results_df['winner'] == 'Draw'] and merged_international_results_df.loc[merged_international_results_df['penalty_winner'].isnull() == False]:
    merged_international_results_df['winner'] = merged_international_results_df['penalty_winner']

The output I get is

The truth value of a DataFrame is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

How can I correct this?