Singles
2018 MercedesCup
Final
Champion	Roger Federer
Runner-up	Milos Raonic
Score	6–4, 7–6(7–3)
Details
Draw	28 (4 Q / 3 WC )
Seeds	8
Events
Singles Doubles
←  2017 · Stuttgart Open ·  2019 →

Lucas Pouille was the defending champion, but lost in the semifinals to Milos Raonic.

Roger Federer won his first title in Stuttgart, defeating Raonic in the final, 6–4, 7–6^(7–3). By reaching the final, Federer regained the ATP no. 1 singles ranking. This was his record extending 18th Grass Court Title and his final ATP 250 title before retiring in 2021.

The top four seeds receive a bye into the second round.

	Semifinals							Final
	1	Roger Federer	62	6	77
	4	Nick Kyrgios	77	2	65
								1	Roger Federer	6	77
								7	Milos Raonic	4	63
	7	Milos Raonic	6	77
	2	Lucas Pouille	4	63

	First round							Second round							Quarterfinals							Semifinals
								1	R Federer	3	6	6
	Q	M Youzhny	65	3					M Zverev	6	4	2
		M Zverev	77	6											1	R Federer	6	6
		G Pella	6	6												G Pella	4	4
		J Millman	2	2					G Pella	77	6
	Q	P Gunneswaran	78	2	6			Q	P Gunneswaran	64	3
	6	D Shapovalov	66	6	3																	1	R Federer	62	6	77
																						4	N Kyrgios	77	2	65
								4	N Kyrgios	6	4	6
		M Marterer	3	6	6				M Marterer	4	6	3
	LL	V Galović	6	4	1										4	N Kyrgios	6	3	6
		G Simon	6	6											8	F López	4	6	3
	Q	M Viola	0	3					G Simon	66	4
		V Troicki	1	0r				8	F López	78	6
	8	F López	6	0

	First round							Second round							Quarterfinals							Semifinals
	7	M Raonic	710	6
		M Bašić	68	2				7	M Raonic	6	6
		M Fucsovics	6	6					M Fucsovics	2	4
	Q	D Kudla	3	4											7	M Raonic	77	77
		B Paire	64	6	6										3	T Berdych	62	61
		T Fritz	77	3	2				B Paire	63	4
								3	T Berdych	77	6
																						7	M Raonic	6	77
	5	P Kohlschreiber	62	63																		2	L Pouille	4	63
		D Istomin	77	77					D Istomin	6	6
		F Mayer	6	6					F Mayer	3	4
	WC	Y Maden	4	1												D Istomin	4	77	3
	WC	R Molleker	6	65	6										2	L Pouille	6	65	6
		J-L Struff	4	77	3			WC	R Molleker	3	4
								2	L Pouille	6	6

	First round							Qualifying competition
	1	Mikhail Youzhny	6	6
		David Guez	2	3
								1	Mikhail Youzhny	6	6
								PR	Egor Gerasimov	3	2
	PR	Egor Gerasimov	77	6
	5	Matthias Bachinger	65	4

	First round							Qualifying competition
	2	Lukáš Lacko	77	5	1
	WC	Tim Pütz	63	7	6
								WC	Tim Pütz	3	61
									Matteo Viola	6	77
		Matteo Viola	6	6
	6	Andrej Martin	4	3

	First round							Qualifying competition
	3	Ruben Bemelmans	5	64
		Christian Harrison	7	77
									Christian Harrison	3	6	3
								8	Prajnesh Gunneswaran	6	4	6
		Evan King	1	4
	8	Prajnesh Gunneswaran	6	6

	First round							Qualifying competition
	4	Denis Kudla	77	6
		Jan Choinski	64	3
								4	Denis Kudla	3	6	6
								7	Viktor Galović	6	4	3
	WC	Philipp Petzschner	1	4
	7	Viktor Galović	6	6

• Main draw
• Qualifying draw