Following his heated argument with Kourtney Kardashian who is rumored to be pregnant again, Scott Disick was spotted out in Calabasas on Tuesday grabbing lunch with some friends.

The "Keeping Up with the Kardashians" star, who is said to be expecting her third child with boyfriend Disick, is currently fighting a lawsuit with male model Michael Girgenti, who claims to be the biological father of her 3-year old son Mason Dash DIsick.

Radar Online obtained a baby photo of Girgenti and placed it next to Mason's baby photo in comparison. The model dared the Kardashians to deny the "spitting image" between he and Mason.

"If Mason is Scott's son, more power to him," the model told Star magazine. "But if he's mine, I need to be with him, to be a part of his life."

The allegations of the paternity suit is said be causing a strain between Disick and Kardashian, who also have a daughter together, Penelope, 1.

[To see the photo of Michael Girgent and Mason Dash Disick side by side along with other pictures click HERE]

According to the Daily Mail, Girgenti wrote a letter to the couple urging them to submit a paternity test, he said, "My attentions [sic] are not to hurt the family you've created with Scott."

"Please take this final request for a DNA test seriously," he went on to say, "Because if you don't, I will be forced to take legal action and sue."

He added, "I assure you I don't take being a father lightly. I will be a great father to Mason."

Girgenti filed paperwork at a Los Angeles County Superior Court against Kim Kardashian's older sister in a bid to get joint custody of Mason after alleging that he had unprotected sex with the reality star nine months before the boy's birth.

A hearing has been set for next month.