The man suing Gwyneth Paltrow over a 2016 skiing collision has told a jury he was rammed from behind by the actress and sent “absolutely flying” at a upscale Utah resort.

“All I saw was a whole lot of snow. And I didn’t see the sky, but I was flying,” said Terry Sanderson, a 76-year-old retired optometrist, calling it “a serious smack”.

That’s the opposite of what Paltrow testified last week, when she said Dr Sanderson was uphill from her and hit her from behind. Dr Sanderson is suing Paltrow for more than $US300,000 ($451,230), claiming she skied recklessly and that he has permanent brain damage from the crash that altered his personality.

On the stand, Paltrow had said Dr Sanderson knocked into her gently from behind but the collision escalated as the two skidded down the beginner slope.

She said his skis veered between her legs, causing her to briefly panic as she heard a man groaning behind her. Paltrow was again in court on Monday.

However, Dr Sanderson recalled a screaming woman skiing out of control and hitting him square in the back. He said he heard a “blood-curdling scream” shortly before the collision that sounded “like someone was out of control”, and that he had never been hit so hard skiing.

Craig Ramon, another skier who said he was the sole eyewitness to the collision, testified last week he saw Paltrow hit Dr Sanderson.

Both sides agree the two then fell down, with Paltrow landing on top of Dr Sanderson. Paltrow’s lawyers have disputed the extent of Dr Sanderson’s injuries and post-crash disorientation, but both sides agree the collision resulted in Dr Sanderson’s four broken ribs and a concussion.

Dr Sanderson was brought to tears throughout his testimony on Monday (local time), particularly when he appeared not to be able to focus or remember things.

His legal team attempted to present his confusion and memory lapses to support their brain-damage argument. Paltrow’s lawyers used it to undercut his reliability as a witness.

After four-and-a-half days of Dr Sanderson’s lawyers calling witnesses, Paltrow’s defence team has equal time to present their case. They called one of her family’s four ski instructors to the stand on Monday afternoon. Her two teenage children, Moses and Apple, are also expected to testify later on.

Jurors watched an animated recreation of the scene on the ski trail.

Jurors sat transfixed as Paltrow’s lawyers played computer-animated reconstructions of how they say the collision occurred, with high enough resolution to show trees, children’s ski coats and show the crash from multiple vantage points.

For their first witness, the defence called Eric Christiansen, a mustachioed 40-year veteran ski instructor at Deer Valley Resort who was giving a lesson to Paltrow’s family. He said he was monitoring much of the mountain during the exact moment Dr Sanderson and Paltrow crashed, but saw what happened immediately before and after.

In testimony that wandered into instruction about skiing technique, Mr Christiansen said Paltrow was making “short radius turns” while Dr Sanderson was skiing down the groomed run “edge to edge” and “quite dynamically”.

He said he remembered Paltrow landed on top of Dr Sanderson because he approached and took her skis off, then his.

“I believe you told me once if a soccer player takes out someone’s legs, they’re underneath,” Paltrow’s lawyer, Steve Owens, said as he asked questions about the crash.

Paltrow’s lawyers have said they also plan to depose a slate of duelling medical experts who are expected to undercut testimony from neurologists, radiologists and psychologists hired by Dr Sanderson’s team.

The trial has touched on the habits and hobbies of wealthy people like Dr Sanderson and Paltrow, as well as the power – and burden – of celebrity. The amount of money at stake for both sides pales in comparison to the typical legal costs of a multiyear lawsuit, expert witnesses, a private security detail high-resolution animations.

Much of the questioning through the trial’s first five days has revolved around Dr Sanderson’s motivation for suing Paltrow. Her lawyers have argued the lawsuit is an attempt by an “obsessed” man to exploit the actor-turned-lifestyle influencer’s wealth and celebrity.

Dr Sanderson’s lawyers have attempted to paint Paltrow as a carefree movie star who hurt an ageing man and is unwilling to take responsibility for the fallout.

“No one believed how serious my injuries were,” said Dr Sanderson, who enjoyed wine tasting and international travel before the crash.

“There was lots of insults added to that singular incident.”

– AAP