Raj's new girlfriend may threaten to hurt his friendship with Penny in the next all-new episode of "The Big Bang Theory."

In the last episode, which was titled "The First Pitch Insufficiency," Howard Wolowitz bit off more than he can chew after he agreed to throw the first pitch at a Los Angeles baseball game in spite of the fact that he has no athletic ability whatsoever. Despite his preparation and practice, Howard could not throw a good pitch and received jeers from the crowd, especially from his best friend Raj, reports Entertainment Weekly.

Plus, Leonard and Penny had a less than fun time when they agreed to double date with Sheldon and Amy. During their outing, Sheldon insisted that their relationship was inferior to his and Amy's. However, Sheldon's taunting forced Penny and Leonard to discuss their fears about getting married.

"Marriage is scary," Leonard told his fiancée after they stepped aside. "You're scared, I'm scared. But it doesn't make me not want to do it. It just makes me want to hold your hand and do it with you."

In Monday's upcoming episode, Penny will be perplexed as to why Raj's new girlfriend Emily, played by guest star Laura Spencer, doesn't seem to like her.

One reason could be because she may believe that Penny and Raj slept together since Penny allowed him to tell the gang that they did in order to save face.

CBS issued a press release and synopsis for "The Hook-Up Reverberation," which states that "Raj's honesty about his past comes back to haunt him after his girlfriend, Emily, is cold to Penny. Also, the guys consider becoming part-owners in Stuart's comic book store."

"The Big Bang Theory" Season 8, Episode 4, "The Hook-Up Reverberation," will air Monday, Oct. 6 at 8:00 p.m. ET on CBS.