Speeding drivers were racing at 100mph when they killed a father travelling home from his son's university graduation, court hears.
Thomas Russell, 39, and Adrian Wojciechowski, 29, weaved through traffic and tail-gated each other at speeds of over 100mph in their Mercedes and BMW cars for four miles, a jury heard.
But when the dual carriageway went into a single lane Wojciechowski broke sharply and lost control of his white BMW 335d which collided head-on with a Land Rover Freelander.
Driver David Grant-Jones, a 49-year-old oil rig tool manager, was killed instantly. His wife Heather, 60, suffered serious injuries including fractures to her foot and ribs.
The couple had attended their son Kristian's graduation at Portsmouth University and were driving home to Weymouth, Dorset, at the time.
Although it was Wojciechowski's BMW that crashed with Mr Grant-Jones, both motorists were charged with causing death by dangerous driving as they were 'equally culpable'.
The fatal collision occurred at 4.40pm near Bere Regis on the A35 on July 14 last year.
The court heard that it was a dry day, with 'good' road surface conditions. The defendants, who apparently did not know each other, 'egged each other on' as they drove in the same direction.
Simon Jones, prosecuting, said: "The defendants were deliberately racing each other. That decision and action was dangerous and led to both defendants reaching high speeds on that bypass.
"They were egging each other on, undertaking dangerous overtaking manoeuvres. Witnesses estimated they were travelling at speeds of over 100mph.
"Their two vehicles carried too much speed off the dual carriageway when it went to a single lane and the vehicles in front were slowing.
"Thomas Russell, who was in front, managed to get his Mercedes into the lane but Adrian Wojciechowski could not stop in time and hit the rear bumper.
"He took evasive action and crossed into the other side of the road where he hit Mr Grant-Jones' Land Rover head on. Tragically, he didn't leave him any time to react.
"While Mr Russell's car didn't connect with Mr Grant Jones', the prosecution argues he is equally culpable in causing the collision which led to the tragic death of Mr Grant-Jones and serious injury to others."
Mr Jones said another witness, on a BMW motorcycle, pulled over into a layby as he was concerned about Wojciechowski 'tailgating' him.
He had reached speeds of 160mph to try and get away from him, but when he slowed down to 100mph, Wojciechowski would be on his back wheel 'within 15 to 20 seconds', the court heard.
During proceedings, the jury was shown pictures of the scene of the crash that also left two of Wojciechowski's passengers injured.
Wojciechowski, who was absent from court, was found to have cannabis in his system at the time of the incident. At his police interview, he answered 'no comment' to all questions.
Russell, who had stopped at the scene, told police the journey until then had been 'unremarkable', although he admitted 'misjudging the speed of the cars ahead and braking rather sharply'.
In a victim impact statement read to the court, Mrs Grant-Jones, who still has to rely on crutches 16 months later, said: "Dave and I had known each other for 28 years and were married for 18 years.
“Dave was a cautious and patient driver. I always felt safe with his driving.”
She said that the last conversation the couple had before the accident was about what takeaway they would have that night.
Mrs Grant-Jones added: "The next thing I remember is lying on the grass in a nightmare. I remember someone holding my hand and asking me questions and being wheeled into the helicopter.
"I knew Dave had died because I kept asking about him, but no one would tell me."
Both Wojciechowski, of West Molesey, Surrey, and Russell, of Ferndown, Dorset, deny causing death by dangerous driving.
The trial, which is expected to last two weeks, continues at Bournemouth Crown Court.