Residents say the man was lying motionless in the middle of the road while a woman was seen trying to help him after coming out of her car.
Eyewitnesses say the incident happened last night near the traffic lights outside CJ's Fish and Chip shop along Malpas Road.
One resident, who did not want to be named, said: "A woman was knocked down on Malpas Road a few months ago but [the police presence] was nothing like it was last night so I thought that was strange.
"Police taped off a large part of the road, and it was closed for a bit."
A 55-year-old cyclist suffered head injuries and is in a stable condition after reports of an attack outside a fish and chip shop in the Malpas area of Newport last night.
The man from Newport was taken to the Royal Gwent Hospital, where he remains this morning.
Police were called to reports of an assault on Malpas Road near the shop at around 10.30pm last night.
A 22-year-old man and a 19-year-old woman, both from the Newport area, have both been arrested on suspicion of assault. They remain in police custody at this time.
Anyone who may have witnessed the incident is asked to ring 101 quoting log 539 21/05/14.