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Jon Rahm hopes the Ryder Cup "does not suffer" if more players join the new Saudi Arabian-funded LIV Golf series.
The Spaniard is defending his US Open title at Brookline this week, the scene of a memorable United States victory against Europe in the 1999 Ryder Cup.
The world number two said: "The Ryder Cup is the biggest attraction the game has to bring new people in.
"I hope we don't lose the essence and the aspect that the Ryder Cup is. That's one of my biggest concerns."
He added: "It's an event we all play for free, and it's one of our favourite weeks, win or lose. I think that says a lot about the game and where I wish it would be at."
European players need to be a member of the DP World Tour to be eligible to play in the biennial event, which will next be contested in Rome in September 2023, while Americans need to be members of the PGA Tour.
PGA of America chief executive Seth Waugh said last year: "If someone wants to play on a Ryder Cup for the US, they're going to need to be a member of the PGA of America and they get that membership through being a member of the (PGA) Tour."
However, the PGA Tour has suspended all of its members that have played, or signed up to play, in LIV Golf events. The DP World Tour is yet to comment on the issue despite repeated requests.
Americans Bryson DeChambeau and Dustin Johnson, who both played in the record 19-9 victory at Whistling Straits last September, are among those to join LIV Golf.
Patrick Reed, who played in three editions between 2014 and 2018, will play in the second event.
On the European side, Ryder Cup stalwarts Ian Poulter, Lee Westwood and Sergio Garcia have also defected to the start-up circuit.
"Are they going to be able to play Ryder Cup or not, the players that went?" asked Rahm.
"In my mind, Sergio, even if he is not breaking 90, he's a no-brainer pick, right? So what's going to happen?
"You have quite a few young Americans. Bryson went, somebody that's probably going to be on the team in the future. Phil's [Mickelson] captaincy is probably in question now.
"I have no idea what's going on or what's going on with the European Tour. I don't know what's going to happen."