The Utah ski crash trial involving Gwyneth Paltrow and retired optometrist Terry Sanderson is heating up, as both sides attempt to prove they were not responsible for the collision that allegedly left Sanderson badly injured.

On Monday, Paltrow's lawyers called into evidence a recreation video of the accident scene, as described from the vantage point of ski instructor Eric Christiansen.

Christiansen, who was hired by Paltrow to teach her then 9-year-old son Moses how to ski, confirmed that the animated video was an accurate representation of how he recalled the events of the day.

"When you're working with students, especially if they're children, you're always looking around. It's very much like driving, you're very aware of everything around you," Christiansen explained referring to why he originally noticed Sanderson making "round, and large and fairly fast" turns on the Deer Valley slope.

"The one thing this animation does not show is I actually watched him make several turns down. And that's what caught my eye…Mr. Sanderson has some very strong skiing skills, because he was skiing edge to edge," Christansen added of the plaintiff.

GWYNETH PALTROW ACCUSER TESTITIES IN SKI COLLISON TRIAL, DESCRIBES 'BLOOD-CURDLING SCREAM'

Christansen alleges that he was skiing on the left side of the "Bandana" trail with Moses while Paltrow was on the skiers' right, making "short-radius turns."

Throughout Christiansen's testimony, Paltrow's lawyer, Steve Owens, would pause and play the recreation, asking the ski instructor to confirm if what was being shown was indicative of that day.

Sanderson is suing Paltrow for $300,000, alleging she caused serious harm to him when she collided with him on a trail at Deer Valley resort.

GWYNETH PALTROW PREPARES TO TAKE THE STAND AS HER COURTROOM APPEARANCES GO VIRAL

"They were on the slope, and she was underneath, and he was on top of her," Christiansen explained of how he discovered both Paltrow and Sanderson, after hearing a loud noise.

"They both had their heads uphill, both sets of skis were still on both she and Mr. Sanderson… Their skis were below them. And they were basically lying, pretty much on their backs," Christiansen explained.

Paltrow recalls realizing something was wrong when "two skis came between my skis forcing my legs apart and then a body pressed against me…My brain was trying to make sense of what is happening," she testified. "I thought, ‘Is this a practical joke? Is someone doing something perverted?’ My mind was going very, very quickly, and my mind was trying to ascertain what happened."

Paltrow has maintained her story that Sanderson skied into her from behind.

CLICK HERE TO SIGN UP FOR THE ENTERTAINMENT NEWSLETTER

The testimony from Christiansen and Paltrow directly contradicts the testimony given by Sanderson's friend and first witness, Craig Ramon, who claims he saw the collision happen.

"We were skiing down the run, and then I heard this yell, this scream," he said. "I looked over … and then I see this skier just slam into the back of Terry, very hard. She hits him right directly in the back. His skis, the tips go out like this, and he falls face down kind of spread eagle."

Sanderson gave a similar recount, explaining. "There was nothing in front of me…I just remember everything was great, and then I heard something I’ve never heard at a ski resort."

"It was like somebody was out of control and hit a tree and was going to die, and that’s what I had until I was hit."

The retired optometrist said he was hit in the back and felt the two fists along with ski poles between his shoulder blades.

Fox News Digital's Lauryn Overhultz contributed to this report.