After Matt Barnes’ tweet, what message will Doc Rivers send?

The first real test of the Doc Rivers era has appeared, and it can appropriately be described in less than 140 characters.

Can the new Clippers coach practice the same toughness that he preaches?

Less than a month into his first season as the Clippers’ $7-million savior, Rivers must start by repairing his own locker room after one of his players threatened to blow it apart.

The player’s name is Matt Barnes, his motive was anger, his weapon was Twitter, and 20 seconds worth of his insensitive typing could rattle this team for weeks.

In the middle of the Clippers’ 111-103 victory over Oklahoma City on Wednesday night at Staples Center, after he had been ejected from the game for shoving Serge Ibaka, Barnes questioned his teammates’ toughness with a tweet that contained a racial slur.

On Thursday morning, Barnes publicly apologized for the tweet. Several hours later, the NBA fined him a relatively light $25,000. But the real test will come Friday morning, when the team meets for the first time since the incident and Rivers must figure out how to punish the popular Barnes while strengthening any bonds he has frayed.

“Adversity is good, it always is,” Rivers said Wednesday night. “Accept it, embrace it, enjoy it.”

Well, he’s got it, the adversity emerging just before halftime Wednesday night, when Barnes was ejected in the final seconds of the first half for shoving Ibaka after the Thunder forward was tangled up with Blake Griffin. Barnes retired to the locker room and, while stewing there in the second half, used his Twitter account to express his rage with a racial slur and profanity.

He wrote, “I love my teammates like family, but I’m DONE standing up for these … All this … does is cost me money.”

The message was tweeted to his 230,000-plus followers and, ultimately, to the world. It was later deleted, but teammates and coaches saw or heard about the original tweet soon after the game.

Barnes apologized to everyone in the locker room, then, on Thursday morning, ironically using the same mechanism that caused so much trouble in the first place, he tweeted a detailed apology to the world.

“My poor choice of words & timing do not reflect who or what I am about,” he tweeted, among other things. “I [accept] full responsibility for all my inappropriate action last night & I am truly sorry!”

Several hours later, the NBA had a chance to bring a bit of closure to the incident with a hefty fine or suspension, but the league ordered neither. Instead, Barnes was fined $25,000, a small and strange price for a business that claims to value tolerance.

Two summers ago, Amare Stoudemire of the New York Knicks was fined $50,000 for tweeting a homosexual slur to a fan. Shouldn’t that be at least the equal of tweeting a racial slur about teammates?

The league’s message was that Barnes was fortunate he was only caught using race-related criticism. Mark Cuban, Dallas Mavericks owner, once tweeted referee-related criticism and, like Stoudemire, was fined $50,000.

In the end, for tweeting the most despicable of racial epithets, Barnes was fined the same amount as the Knicks’ J.R. Smith was fined for tweeting a photo of a woman on his bed wearing a thong. It was as if officials thought Barnes was playing a dumb practical joke or using a bit of bad judgment.

Give the Clippers credit for knowing better.

“The choice of words, obviously, that’s a word that I’m not a fan of in all venues,” Rivers said Wednesday night.

Now Los Angeles will learn the extent of Rivers’ disappointment, which could help define the start of Rivers’ tenure here. Though the NBA’s agreement with the players’ union prevent the Clippers from administering formal punishment beyond the league’s action, there are ways Rivers could make a statement here.

Rivers could cut Barnes’ 19 minutes per game down to single figures for a night, or even leave him on the bench for an entire game. Rivers could order Barnes to make a public statement that puts a remorseful voice and face to his tweets.

The new coach will meet with Barnes and the team Friday, at which point Los Angeles will have a better understanding of Rivers’ renowned definition of toughness.

Barnes, whose hardened on-court persona is diametrically opposed to his kind and thoughtful off-court nature, was actually defying toughness in his tweet. If he really wanted to call out his teammates about their fortitude, shouldn’t he have done it to their faces? And should the context of the racial slur really mitigate the offensiveness of its use?

It shouldn’t matter that he was an African American using it in relation to his predominantly African American teammates. There should be no difference if he was using it in relation to locker-room buddies or a group of strangers.

When he typed the word on a worldwide public forum, he lost all room for debate.

His Clippers teammates, meanwhile, seemed more upset with the tweet’s implications. They love Barnes’ muscle, but they worry about his head. They respect him as a teammate, but they feel his form of playground aggressiveness is counterproductive in an NBA arena.

“I think, at times, toughness can be mistaken in the form of being ready to fight and stuff like that,” said Chris Paul. “Toughness comes down to basketball. At the end of the day, ain’t nobody in the NBA holding the world championship belt, you know what I mean?”

Everyone knows what Paul means, especially Griffin, who seemed particularly offended that Barnes felt a need to shove Ibaka in order to protect him. The two men had just untangled their arms when Barnes charged Ibaka with a shove. Griffin has spent his entire young career defending himself against charges that he isn’t tough enough. Now that he is finally beginning to play with a resolute physicality, he’s clearly tired of hearing about it.

“It happens, guys push after the play.…I didn’t personally feel a need to do something in order to get myself ejected,” Griffin said. “Like Chris said, to me, toughness isn’t just being ready to throw a punch or push somebody and be tough like that, it’s about having that mental toughness as well to stay in the game.”

In the second half Wednesday, while outscoring the Thunder 58-41, the Clippers clearly showed they have mental toughness to win even without Matt Barnes.

Beginning Friday, Doc Rivers must now figure out how to win with him.

bill.plaschke@latimes.com

Twitter: @billplaschke