ZADAR, Croatia -- Serena Williams isn't getting much support from the men on the United States' Davis Cup team over her insinuation that sexism played a role in the code violations she received during the US Open final.

Then again, Steve Johnson, Mike Bryan and Ryan Harrison are trying their best to stay out of the debate since Carlos Ramos, the chair umpire who penalized Williams, is also handling their best-of-five semifinal series against Croatia this weekend.

"It's been polarized and in some ways politicized," U.S. captain Jim Courier told The Associated Press on Thursday. "But we have no doubt that Carlos was just enforcing the rules as he sees them."

Williams was given three code violations by Ramos in her straight-set loss to Naomi Osaka on Saturday, and Williams and critics inside and outside of tennis argued that she wasn't treated the same as some male players.

"Look, I don't want this to come out the wrong way," Johnson said. "But he enforced rules that have been enforced on me over the years.

"I've never been called for coaching, but the racket abuse, the verbal abuse," Johnson added. "That's just part of the sport. I think a lot of it maybe got overamplified because it was the finals of the US Open."

USTA president and CEO Katrina Adams was overheard apologizing to Ramos on the sidelines of the draw ceremony. A USTA spokesman said Adams was not speaking to media, while Ramos was not available for questions.

Courier said there was nothing to discuss with his team over Ramos.

"We're here to play; Carlos is here to umpire; and we don't expect anything out of the ordinary," Courier said.

While Ramos is known as a stickler for the rules, the U.S. team won't have to worry about coaching violations since captains sit courtside during Davis Cup matches and are permitted to give advice throughout the match.

During the final against Osaka, Williams got a warning for violating a rarely enforced rule against receiving coaching from the sidelines. An indignant Williams emphatically defended herself, denying she had cheated. A short time later, she smashed her racket in frustration and was docked a point. She protested and demanded an apology from the umpire, who penalized her a game.

"He's always been a fair, level-headed guy and made a decision in the heat of the moment. If it was wrong or right, I'm not the judge," said Bryan, a doubles specialist.

"I think we're all cognizant of the fact that three strikes and you're going to get a game penalty," Bryan added. "I don't think we would ever try to push it that far, especially in this Davis Cup format -- we're not going to dock our country a game. You don't really crack rackets or berate umpires in this format; you kind of look to your team for support."

Marin Cilic, Croatia's top player, also had nothing but respect for Ramos. Although Cilic, the 2014 US Open champion, noted: "I'm not a guy that gets too many code violations. ... I'm quite cool."

The 51st-ranked Harrison, who was called in as a late replacement for the injured Jack Sock, said the women's final "was a very touchy situation."

"It's hard to say one side or the other without causing a big stir," Harrison said. "In a situation where we know Serena is unbelievable; she's iconic; and we know that Carlos is there because he's worthy of being there for those matches.

"I know Carlos, and I know he's not looking to put himself in a difficult position. I truly believe he was trying to do what he felt like was right at the time and always in heated situations it's going to be a very sticky, sticky spot whenever it's in a Grand Slam final like that."

Against Croatia, Johnson will face Borna Coric in Friday's opening singles match, followed by Cilic versus Davis Cup debutant Frances Tiafoe.

In Saturday's doubles, Ivan Dodig and Mate Pavic will face Bryan and Harrison. The reverse singles are on Sunday.

The winner will meet either France or Spain in the final.

The Americans are missing their top two players: No. 10 John Isner is staying home while his wife awaits the birth of their child, and Sock hurt his hip en route to winning the US Open doubles title with Bryan.

"The one thing we know about Davis Cup is that rankings rarely matter," Courier said. "Davis Cup is highly unpredictable and playing for your country can affect people in different ways, shapes and forms."