Andre Agassi was the defending champion but lost in the semifinals to Mardy Fish.

Andy Roddick won in the final 7–6^(15–13), 6–4 against Fish.

A champion seed is indicated in bold text while text in italics indicates the round in which that seed was eliminated.

	First round							Second round							Quarterfinals							Semifinals							Final
	1	A Roddick	6	6
		C Rochus	4	2				1	A Roddick	6	6
		K Vliegen	6	6					K Vliegen	2	3
		A Popp	1	3											1	A Roddick	6	79
		N Kiefer	7	5	2											J Johansson	3	67
		J Johansson	5	7	6				J Johansson	6	6
	Q	Z Fleishman	1	3				7	J Blake	4	2
	7	J Blake	6	6																		1	A Roddick	77	6
	4	T Dent	6	6																		WC	R Kendrick	63	2
		P Goldstein	4	4				4	T Dent	4	4
	WC	R Kendrick	6	6				WC	R Kendrick	6	6
		L Burgsmüller	4	2											WC	R Kendrick	78	4	6
		C Saulnier	6	77												C Saulnier	66	6	3
		B Vahaly	3	64					C Saulnier	3	7	6
	Q	C Mamiit	4	3				WC/5	R Ginepri	6	5	4
	WC/5	R Ginepri	6	6																									1	Andy Roddick	715	6
	6	V Spadea	6	6																									3	Mardy Fish	613	4
	WC	T Haas	4	2				6	V Spadea	6	4	4
		H-T Lee	77	6					H-T Lee	2	6	6
		X Malisse	61	1												H-T Lee	2	3
		J Melzer	3	6	3											M Fish	6	6
		K Carlsen	6	4	6				K Carlsen	3	6	62
	Q	A Reichel	1	4				3	M Fish	6	3	77
	3	M Fish	6	6																		3	M Fish	5	6	6
	8	W Ferreira	714	65	1																	2	A Agassi	7	4	2
		J-M Gambill	612	77	6				J-M Gambill	6	6
		D Tursunov	5	6	3			Q	K. J. Hippensteel	3	2
	Q	K. J. Hippensteel	7	4	6											J-M Gambill	64	5
		W Moodie	6	77											2	A Agassi	77	7
		T Martin	4	61					W Moodie	66	4
		I Labadze	64	4				2	A Agassi	78	6
	2	A Agassi	77	6

• 2004 Siebel Open Draw
• 2004 Siebel Open Qualifying Draw