Travis Kelce says he has to keep his girlfriend’s football plans a secret to preserve the sanctity of the sportsbook.

It is a truth universally acknowledged that Taylor Swift’s ability to influence the world extends far beyond her music. From the massive economic impact of her tour stops to her boost of the bead market, it’s clearly Taylor’s world, we just live in it. And according to her presumptive boyfriend, Kansas City Chiefs tight end Travis Kelce, she now has the ability to sway oddsmakers and bookies, to the point that her plans to attend Chiefs games (or not) must be kept secret until betting has closed.

Swift’s presence at a game has been linked to how well Kelce plays since October, when CBS Sports first compared Kelce’s statistics between games when Taylor is in the building and when she is not. The numbers suggest that his yardage nearly doubles with Swift in the stands, the Sporting News reports, a situation that hasn’t been lost on gamblers and those who take their bets.

It’s a situation that came up last month on Kelce’s podcast with his brother Jason Kelce, a center for the Philadelphia Eagles. “When T-Swift is at the game, you are averaging 99 yards. And when you are left with only your friends and remaining family there, you are at 46.5 yards a game,” Jason told his brother, who responded, “How could I not be aware of this?”

According to Amy Howe, the CEO of gambling company FanDuel, betting on Kelce has doubled since his rumored relationship with Swift hit the headlines. “There’s more Kelce betting, that’s for sure,” Howe said at the Global Gaming Conference last month. “Just when you think (Swift) couldn’t conquer anything else, she conquers the sports world too.”

That uptick in interest—as well as the seeming statistical performance correlation—is likely why Kelce refused to comment on Swift’s attendance at his next game. At a press conference Friday, in advance of the Chiefs’ Sunday matchup with the Miami Dolphins at Frankfurt Stadium in Frankfurt, Germany, Kelce was asked if Swift—who has attended four Chiefs games thus far this season—would be traveling to Germany for this weekend’s game.

“When I mention — or everyone knows — she’s at the game, the Vegas [line] and over-under on my catches goes up and down,” US Weekly quotes Kelce as saying in response. “The spread goes up and down. So I don’t want to mess with any of that stuff. I’m just going to keep that to myself.”

Kelce also intends to keep most other details of his relationship to himself. At the press conference—which, again, was intended to discuss an upcoming football game—a reporter asked for the “latest status” of the player’s alleged romance with the singer.

“The latest status is, I got to see her last week,” Kelce said. Then, when a sports journalist asked if he was in love, Kelce firmly responded, “I’m going to keep my personal relationship personal.”

With a Friday dinner date in New York and a Buenos Aires, Argentina Eras tour date set for Thursday, Nov. 9, Taylor Swift’s attendance at Sunday’s game is anyone’s bet. Kickoff for the Kansas City Chiefs game against the Miami Dolphins is at 9:30 a.m. ET on Sunday, Nov. 5.