BRECKENRIDGE, Colo. (Map, News) - The lawyer for an Australian man on trial for hitting a co-worker with a snowball said Thursday it was just "playful action in the snow", not an assault.

Authorities say Andrew Thistleton, 21, hit Michelle Oehlert with the snowball at the Copper Mountain ski resort on Feb. 4. They worked at Breeze Ski Rentals together.

On the opening day of the trial, Thistleton's lawyer Lisa Moses said workers at the ski shop liked to joke around, including throwing snowballs made from snow collected from rented skis inside the shop.

"This is not an assault. This is not harassment. That's not was this is. This is playful action in the snow," Moses said.

Prosecutor Michael Angel told the jury of three men and three women that Thistleton threw a heavy snowball filled with ice at Oehlert as she waited for a bus with her boyfriend. He said Thistleton and Oehlert didn't get along.

"It's not a joke to chuck an iceball at someone from behind who's not looking...This wasn't in good fun. This was malicious and this had intent," Angel said in his opening statement.

Oehlert, who was not in court, told police the blow was painful because she had an injury from a car accident. She also said Thistleton and two other people were taunting her.

Thistleton faces a harassment charge along with the third-degree assault charge, both misdemeanors. He pleaded not guilty in July and flew back to Colorado for the trial with his mother.

Police said Thistleton told them he threw the snowball and wanted to apologize, but he denied saying anything offensive to Oehlert.

Witnesses are scheduled to testify Friday and a verdict is expected by the end of the day