On Saturday, Kim Kardashian and Odell Beckham Jr. arrived together at The Wynn in Las Vegas, one of their first appearances since going exclusive. The couple were first linked together in September of last year, but a source told DailyMail.com on Friday that the romance went back even further.

“Kim has been romantically involved with Odell since last summer and thought she had managed to keep it under wraps,” said the insider. “She is not seeing anyone else right now—at least not that her close friends know of.”

The Baltimore Ravens wide receiver was wearing black and white pants and a matching leather jacket with star details along the sleeves as he led Kardashian through the lobby. The SKIMS founder was wearing a backless top with a deep neckline and a pair of bell-bottom leggings, both in dark brown. She accessorized with a black fedora pulled down low over her forehead and her hair was down and straight. The pair are in Vegas for Sunday’s Super Bowl.

Beckham Jr. split last year from his former girlfriend Lauren Wood, with whom he shares a one-year-old son named Zydn. A second source told US Weekly that the new pair are “getting serious,” but will still probably not be very public with their relationship.

“Odell’s personality is much more private than Kardashian’s,” said the insider, describing him as more “low-key, while Kim’s more accustomed to the limelight,” and explaining that they are “trying to figure out the next steps.”

Another insider told Entertainment Tonight, “Things have been continuing to heat up between Kim and Odell. They like each other and have a good thing going. Odell likes to keep a low profile and Kim appreciates that. They have been friends for a long time and naturally vibe with one another. Things are just easy between them and he isn’t in it for the attention or spotlight.”