According to The Sun, K-Pez was having lunch with Mayer at The Polo Lounge in Beverly Hills when Russell turned up - leaving the Part Of Me singer running for cover in a bid to avoid the comedian.
A source told the newspaper: "As soon as Katy saw Russell she hid under the table. When he was directed to one far away she emerged.
“John threw some money on the table and they headed to the back door and their waiting car."
They added: “Russell didn’t seem to see a thing but everyone in the restaurant saw what happened.”
Last month, the former couple had another awkward run-in while watching an LA Lakers game at the Staples Center in Los Angeles, sitting at opposite sides of the court.
It is thought that the Teenage Dream star and Brand did not speak to each other throughout the game and despite being so close, they managed to avoid any eye contact.
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