AceShowbiz - Sources reveal that Reese Witherspoon and Blake Lively, once rumored rivals, are now embroiled in a heated battle over projects based on the works of Australian author Liane Moriarty.

Witherspoon, 48, is determined to launch a third season of her hit series "Big Little Lies," which is adapted from Moriarty's book of the same name. However, insiders claim Witherspoon is triggered by Lively, 36, who is "pushing hard" to bring Moriarty's novel "The Husband's Secret" to the screen.

"Reese doesn't appreciate copycats," a source told the National Enquirer. "She believes she deserves credit for introducing American TV viewers to Laine's stories."

The actresses' rivalry has reportedly escalated as they vie to join Taylor Swift's anticipated entry into filmmaking. However, insiders speculate that Lively has the edge due to her close friendship with the singer.

Despite selling her production company, Hello Sunshine, for $900 million, Witherspoon is said to be driven and intent on outperforming her previous successes. "She's pitching and selling shows and films in a competitive market," a source said.

In contrast, Lively is reportedly benefiting from her business-savvy husband, Ryan Reynolds, who advises her on her endeavors.

The brands created by Witherspoon and Lively has also drawn comparisons to that of Gwyneth Paltrow, who expressed annoyance at the media's tendency to generalize and link successful entrepreneurial women.

"I'm slightly offended by this sort of generalization that happens with myself and Jessica [Alba] and Reese and Blake," Paltrow said. "Our businesses are very different."

RadarOnline.com has reached out to Witherspoon and Lively's representatives for comment.