Motorcyclist, 44, from Klemzig still fighting for life after collision at Hillcrest on Saturday

A 44-year-old male cyclist is in a critical condition, after his motorcycle collided with a car at Hillcrest on Saturday morning.

The Dukes Hwy is closed following two crashes in three hours overnight. Picture: SA Police

A 44-year-old cyclist is fighting for his life, after a crash at Hillcrest on Saturday.

Police and emergency services were called to North East Rd, Hillcreast after reports a motorcycle and a car crashed at 6.05am on Saturday.

The male rider from Klemzig was taken to the Royal Adelaide Hospital, after sustaining life-threatening injuries after the collision.

He is still in a critical condition.

Road restrictions were in place, but have since been lifted.

The driver of the car, a 47-year-old Hillcrest man, was not physically injured.

Police are urging anyone with any information about the crash, to contact Crime Stoppers on 1800 333 000.

A serious accident at Hillcrest has left a motorcyclist with life-threatening injuries after colliding with a car. The 44-year-old rider was rushed to hospital while the driver of the car, a 47-year-old man, was not injured. Details in 7NEWS Adelaide at 6pm. #7NEWSpic.twitter.com/XEnEI4FMhr

— 7NEWS Adelaide (@7NewsAdelaide) July 1, 2023

Meanwhile, the South-Eastern Freeway is open again after earlier being down to one lane on the city-bound side around Bridgewater after a truck broke down.

The truck pulled into the emergency stopping lane about 1km past the Bridgewater entry ramp but was sticking out slightly into the left-hand lane.

Traffic had banked up several kilometres.

The freeway is now cleared.

Traffic banked up on the South-Eastern Freeway after a truck broke down near Bridgewater. Picture: Claire Richter / Facebook

It comes the Dukes Highway was closed after two crashes in fewer than two hours near the Victorian border on Saturday morning.

Police and emergency services were called to the Dukes Hwy at Wolseley after reports a B-double rolled about 2.30am.

On arrival they found the truck on its side, blocking both east and westbound lanes of traffic.

The 25-year-old male driver from Gilles Plains was trapped inside the cabin but was eventually freed by police.

The man suffered minor injuries and was taken to Bordertown Memorial Hospital for treatment.

About three hours later, as emergency services were still at the scene performing traffic control duties, a vehicle crashed into the B-double.

A Kia station wagon approached a road closure point, disregarded directions and drove into the closed-off area.

The truck was still blocking both lanes and the Kia crashed into the truck.

The driver was treated for minor injures and was also conveyed to the Bordertown Memorial Hospital for treatment.

The Dukes Hwy is closed between Creetoona Ave and Ridgeway Rd and is estimated to remain closed until midday.

Police advise motorists to follow instructions at road closures.

Authorities are investigating both incidents and are appealing for anyone who witnessed the truck rollover to contact Crime Stoppers.