The United States didn't show much fight in the 2018 Ryder Cup.

But when it was all over, the gloves almost came off — among teammates.

According to multiple reports, including by The Telegraph and later confirmed by Golf Channel's insider Tim Rosaforte, Team USA stars Dustin Johnson and Brooks Koepka, two of the most mild-mannered men on the golf course, nearly came to blows Sunday night while hanging out in the European team room.

The exchange was reportedly heated and the two had to be separated, according to multiple witnesses.

Golf Digest reported that Pauline Gretzky, Johnson's fiancee, and Jena Sims, Koepka's girlfriend, also were involved in the incident.

Another report from French outlet L'Equipe said there had been friction between Johnson and Koepka on Team USA's flight to France for the Ryder Cup.

The news comes as quite a shock as Johnson, 34, and Koepka, 28, are considered good friends, even working out together. Koepka has previously told stories about going to the gym with Johnson, who, inevitably, gets mobbed by fans, while Koepka is able to enjoy his workout in total anonymity, despite being a three-time major winner.

It's just the last tale of animosity among the United States Ryder Cup team, which got blown away by Europe, 17.5-10.5. Also Sunday, Patrick Reed vented to the New York Times about captain Jim Furyk and Jordan Spieth (after which an anonymous Team USA Ryder Cup member blasted Reed). Four years ago, Phil Mickelson famously blasted captain Tom Watson, as Watson sat nearby, stunned.

These incidents continue to lend credibility to the long narrative that the Americans are a bunch of individuals, while the Europeans are much more of a team.

For more proof there, just check out this hilarious social-media post featuring Team Europe stars Tommy Fleetwood and Francesco Molinari, who were so successful together at the Ryder Cup, the nickname "Moliwood" was born:

Johnson and Koepka were paired together in Saturday's afternoon matches and lost, 2 and 1, to the team of Henrik Stenson and Justin Rose.

Koepka went 1-2-1 in his four matches, and Johnson was 1-4 in his five matches.

Europe has won seven of the last nine Ryder Cups, many in dominating fashion.

Twitter: @tonypaul1984