Singles
2018 Croatia Open Umag
Champion	Marco Cecchinato
Runner-up	Guido Pella
Score	6–2, 7–6(7–4)
Draw	28 (4 Q / 3 WC )
Seeds	8

Andrey Rublev was the defending champion, but lost in the quarterfinals to Robin Haase. This was Rublev's first tournament back on tour after missing three months due to a stress fracture in his back.^[1]

Marco Cecchinato won the title, defeating Guido Pella in the final, 6–2, 7–6^(7–4).

Seeds

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

Draw

Finals

	Semifinals							Final
		Guido Pella	6	1	6
	6	Robin Haase	3	6	2
									Guido Pella	2	64
								3	Marco Cecchinato	6	77
	3	Marco Cecchinato	6	6
	Q	Marco Trungelliti	2	1

Top half

	First round							Second round							Quarterfinals							Semifinals
								5	A Ramos Viñolas	3	6	0
		D Lajović	7	6					D Lajović	6	1	6
		N Basilashvili	5	2												D Lajović	63	5
		G Pella	1	6	6											G Pella	77	7
		T Daniel	6	3	3				G Pella	5	6	6
		A Bedene	77	4	6				A Bedene	7	4	4
	7	J Sousa	65	6	4																		G Pella	6	1	6
																						6	R Haase	3	6	2
								4	A Rublev	6	64	6
	WC	F Auger-Aliassime	6	6				WC	F Auger-Aliassime	4	77	3
	LL	A Martin	4	3											4	A Rublev	3	66
	Q	M Kližan	6	6											6	R Haase	6	78
		N Jarry	2	0				Q	M Kližan	6	4	3
	Q	R Dutra Silva	6	5	3			6	R Haase	3	6	6
	6	R Haase	4	7	6

Bottom half

	First round							Second round							Quarterfinals							Semifinals
	9	M Marterer	3	7	6
	WC	N Serdarušić	6	5	3			9	M Marterer	64	3
		L Đere	6	1	6				L Đere	77	6
		P Cuevas	4	6	3											L Đere	4	1
	Q	S Travaglia	3	6	2										3	M Cecchinato	6	6
		J Veselý	6	3	6				J Veselý	6	5	5
								3	M Cecchinato	2	7	7
																						3	M Cecchinato	6	6
	8	B Paire	1	3																		Q	M Trungelliti	2	1
		M Fucsovics	6	6					M Fucsovics	7	4	2
	Q	M Trungelliti	6	6				Q	M Trungelliti	5	6	6
	WC	F Škugor	3	4											Q	M Trungelliti	6	6
		P Lorenzi	3	4												E Donskoy	1	4
		E Donskoy	6	6					E Donskoy	711	3	6
								2	D Džumhur	69	6	4

Qualifying

Qualifying draw

First qualifier

	First round							Qualifying competition
	1	Martin Kližan	2	77	6
		Danilo Petrović	6	62	4
								1	Martin Kližan	6	6
								8	Kenny de Schepper	4	2
		Zsombor Piros	2	65
	8	Kenny de Schepper	6	77

Second qualifier

	First round							Qualifying competition
	2	Rogério Dutra Silva	6	6
	WC	Admir Kalender	3	2
								2	Rogério Dutra Silva	6	5	6
								7	Andrej Martin	2	7	2
		Roberto Quiroz	2	60
	7	Andrej Martin	6	77

Third qualifier

	First round							Qualifying competition
	3	Alexey Vatutin	6	6
	Alt	Nik Razboršek	2	3
								3	Alexey Vatutin	2r
									Marco Trungelliti	3
		Marco Trungelliti	77	6
	5	Facundo Bagnis	64	3

Fourth qualifier

	First round							Qualifying competition
	4	Stefano Travaglia	77	77
		Gian Marco Moroni	63	61
								4	Stefano Travaglia	1	6	6
									Peđa Krstin	6	3	2
		Peđa Krstin	3
	6	Enrique López Pérez	1r

References

• Main draw
• Qualifying draw