T-Mobile's John Legere was escorted out of the AT&T CES party Monday night after a CNET reporter posted a photo with the T-Mo's CEO on Twitter.

An unexpected appearance turned out to be a surprising departure.

T-Mobile CEO John Legere's "secret mission" may not have played out as well as he'd expected. Crashing AT&T's CES party Monday night with his folks to watch Macklemore and Ryan Lewis perform was Legere's plan for the night. Unfortunately for the owner of the fourth largest carrier in the U.S., AT&T does not like its competition snooping around its social gatherings.

The feud between AT&T and T-Mobile is no secret. Both carriers have been trying hard to demean each other by introducing new plans that attract more users. Just a few days ago, Legere called AT&T's new $200 credit offering for switching carriers a "desperate move." The nation's second largest carrier seems to have taken the outspoken CEO's words to heart, which resulted in Legere's ejection from the AT&T CES party Monday night, CNET reports.

CNET News reporter Roger Cheng tweeted his joyful rendezvous with T-Mo's CEO, along with a picture of himself posing with Legere. He captioned the snap pointing out Legere's concealed t-shirt in the company's signature color under his jacket.

Ran into @JohnLegere at the AT&T party. Yep, he crashed it. And still wearing the pink t-mo shirt. #CES2014 pic.twitter.com/gy9vGTJUEW

- Roger Cheng (@RogerWCheng) January 7, 2014

Shortly after Cheng's Twitter account was updated with another tweet, which said Legere had been escorted out of the event by AT&T's security personnel. Flamboyant Legere expressed his aggravation via Twitter, by replying to Cheng's tweet.

@RogerWCheng great to see you! I just love Macklemore! Very bad move by @ATT and #PalmCasino . Have a great night! I am very angry! - John Legere (@JohnLegere) January 7, 2014

Legere has since been retweeting several tweets of his followers, speaking about his ejection  from the lavish event.

On the business front, T-Mobile is readying its own press conference that will be held this Wednesday, which will finally introduce "Uncarrier 4.0" to give the company an edge to "crush the competition." Legere joked that the new plans will go beyond AT&T's $200 offer to switch carriers.