2025 International Challenger Zhangjiagang

Country	Player	Rank1	Seed
AUS	Bernard Tomic	169	1
JPN	Rio Noguchi	196	2
JPN	Sho Shimabukuro	201	3
CHN	Sun Fajing	215	4
JPN	Yasutaka Uchiyama	227	5
GBR	Oliver Crawford	232	6
	Ilia Simakin	238	7
FRA	Arthur Géa	257	8

• ¹ Rankings are as of 18 August 2025.^[1]

The following players received wildcards into the singles main draw:

• Mo Yecong
• Te Rigele
• Xiao Linang

The following player received entry into the singles main draw using a protected ranking:

• Philip Sekulic

The following players received entry into the singles main draw as alternates:

• Luca Castelnuovo
• Sergey Fomin
• Renta Tokuda

The following players received entry from the qualifying draw:

• Joshua Charlton
• Huang Tsung-hao
• Yuta Kikuchi
• Filip Peliwo
• Kaichi Uchida
• Kaito Uesugi

The following player received entry as a lucky loser:

• James Watt

• Sho Shimabukuro def. Oliver Crawford 6–3, 3–6, 7–5.

• Luca Castelnuovo / Akira Santillan def. Petr Bar Biryukov / Alexandr Binda 6–3, 6–7^(8–10), [10–3].