Answer the following question based on the text below:
"""Text
NAME_1: Tennis. He is a Serbian professional tennis player who is currently ranked world No. 1 by the Association of Tennis Professionals (ATP). He has won 20 Grand Slam singles titles, tied for the most in history with NAME_2 and NAME_3. He is also the only player to complete the career NAME_4, winning all nine ATP Masters 1000 tournaments at least once.

"""Question
Who has won more grand slams, NAME_2 or NAME_1? The response should be in all capital letters.
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