Donald Trump and Mexico's Former President Vicente Fox Spar on Twitter Before Visit

"Mexico is not yours to play with, show some respect," wrote Fox.

It all started during an interview with CNN this morning, when Fox called Trump a “false prophet” while deriding his planned meeting with Mexico's current President Enrique Peña Nieto.

"Trump is using Mexico, is using President Peña to push his sinking poll numbers," Fox said on CNN's "New Day." “So it's a very opportunistic move and I hope U.S. public opinion, U.S. citizens can see this and finally, and finally see what is behind Trump, this false prophet that is just cheating everybody.”

After Fox’s interview this morning, Trump took to Twitter to fire back at Fox.

Fox was quick to respond, telling Trump to “stop lying” and “show some respect.”

“I’m not going to pay for that f---ing wall! He should pay for it. He’s got the money,” Fox said. “What is Trump? He’s not a Republican. Absolutely not. Those are not the Republican principles. He’s not a Democrat. He is just himself. He is egocentric.”