Emergency services were called to Garratt Lane at 1:30 to reports a motorcycle had been in a collision with a Honda Civic.
A woman in her 30s, who was a passenger on the motorbike was seriously injured and taken to hospital where her condition is critical.
The male rider, in his 40s, was also taken to hospital.
The 22-year-old driver of the car was arrested on suspicion of drug driving causing serious injury and is in custody.
Road closures remain in place.
