Investigators say the driver left the car at the scene and fled.
The entire outbound lanes of the Southwest Freeway were closed for several hours but reopened just after 6 a.m.
The hit-and-run happened on US-59 southbound at Wilcrest in southwest Houston shortly before 4 a.m.
The motorcyclist is described as a 30-year-old man. Police say he was not wearing a helmet when he was hit.
He is in critical condition.
The man's friend was traveling behind him but did not witness the crash. He said the victim was on his way home when the accident happened.
No suspects have been named.
Investigators cut the airbag out of the car involved in the crash. Police say this is so they can possibly test for DNA to verify who was driving the vehicle at the time of crash.
Courtney Fischer is live at the scene and will provide updates as the story develops.
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