Wear the same colors, struggle against the same opponent, strive for the same goal—logic would dictate that teammates be mates (in the Australian sense, not the Darwinian one).
But there is one more thing teammates share that defenestrates the whole friendship thing: limelight.
While there is no "I" in team, there is one in "headline" and a pair both in "prime time" and "interview."
Make no mistake about it: Athletes are sportsmen and sportswomen, but they are also celebrities. And celebrities are notorious attention junkies.
If the Sports Illustrated covers displace Carmelos with Jeremys, Sanchezes with Tebows, Gordons with Johnsons, the letters in "mates" rearrange themselves into "steam." The kind that comes out of ears.
Click on to see 20 sets of current (or very recent) teammates who kind of hate each other.
While the jury may still be out as to whether Chicago QB Jay Cutler and left tackle J'Marcus Webb actually kind of/sort of/maybe hate each other, a September 2012 rebuke and shove during a Bears loss to the Packers has convinced some viewers.
Later, Cutler expressed regret for the shove, but not for the harsh words.
Fellow teammate D.J. Moore stood up for Webb, noting that Cutler should also hold himself accountable for the team's poor performance. (Cutler threw four interceptions in the game.)
Sanchez's contention is that fighters need to engage and not just squeak out a win by points, as he alleges Condit did in his fight against Nick Diaz (UFC 143).
It would be very interesting indeed if Sanchez ever faces Guida or Condit in the Octagon again.
In this case, Arizona Wildcats junior defensive lineman Tevin Hood and freshman linebacker Cody Ippolito got some limelight that they perhaps had not sought.
Their team had just given up 21 unanswered points. Spirits were low. Tensions were high. Conditions rife for reined-in loathings to break free.
But to whomever says hatred can't be productive, let this game be evidence to the contrary. After the teammate scuffle, Arizona made a stunning comeback and took home the title.
Hamrlík got on Brouwer's blacklist by ripping into the players' association chief, Donald Fehr, for his handling of the lockout.
Neuvirth made the list by backing Hamrlík and adding that the lockout was not about the majority, but just about superstars with big contracts.
Brouwer held nothing back, saying the two men were sellouts and acted selfishly:
Me being on their team, how am I going to trust them as a teammate from now on? Because you know they’re not going to support players in the big scheme of things when you go and you play on the team with them; it’s going to be tough to want to back those guys from now on.
At least one other player speculated that once the season started, Hamrlík and Neuvirth might just find themselves undefended targets on the ice.
Pissed off at the decision to allow another team to score as a last-ditch effort to get the ball back, Dockett (pictured left) allegedly launched a missile of the salivary sort at teammate Kerry Rhodes (pictured right).
Though both Rhodes and Dockett deny the spittle shot aspect of the argument, the team fined Dockett just over $100,0000.
And who would have ever thought spittle could be valued at far more than its weight in gold?
Back in October 2012, Broncos receiver Demaryius Thomas caught a one-yard touchdown pass. He and fellow receiver Eric Decker positioned up for an alley-oop goal post dunk when...
Unwitting father figure Brandon Stokley snatched the ball away. Sure, he saved the guys from league fines and the team from a 15-yard penalty, but Thomas and Decker did not appreciate the foiling.
Stokley probably did very little for his popularity when he told the Denver Post: "Now, I've got these other two knuckleheads I've got to mold. These kids, nowadays. You've got to put them in timeout."
Frenchman Charles Pic and German Timo Glock both race for team Marussia F. A few months back, Pic was outracing Glock, who was the team leader.
Glock alleged that Pic was blocking him on the course.
"Maybe he doesn't understand English on the radio," a royally ticked off Glock said to reporters.
After a dismal season, Mike Vick lashed out against his teammates. Vick believed that the other players, not ex-coach Andy Reid, were to blame for the team's failings.
But surely most of the players wouldn't be sorry to see Vick move on for the 2013 season.
Slapping players with red cards for fighting is not at all unheard of in the world of soccer.
The difference here is the two guys whaling on each other play for the same team.
In an act of Michael Vick-dom, Terry recently told his teammates to buck up and start putting in more effort.
Tough words from a guy who had been stripped of his captaincy twice in two years. A guy who had been accused of having an affair with a teammate's girlfriend (and had teammates turn on him as a result).
A guy who has been investigated for alleged racial abuse directed at another player.
Tim Tebow is a polarizing figure. You either love him or hate him, and a number of players on the Jets fall into the latter category.
It's never a good thing when players on your own team think you are terrible.
That is exactly what one unnamed Jet referred to Tebow as.
Back in 2011, there were rumors and speculations that the recently dumped Gasol blamed his misfortune on Kobe (and Vanessa).
Then in May 2012, amid rumors that Gasol was looking to move to Chicago, Sam Smith of Bulls.com wrote this: "And what you hardly need any sources for is to see how [Gasol] and Bryant basically can’t stand one another."
And it couldn't have helped the situation any when that same month, Kobe blamed Gasol for a playoff loss. Check out this postgame interview. Jump to video time 1:50 to hear Kobe stick it to Gasol plainly and simply.
The fiery feud between current Indian national team captain Dhoni and opening batsman Sehwag is now widely known.
The two have been dissing each other at press conferences for some time now. And the media are having a field day with it. Check out the computer-generated purple lightning bolt of hatred in this India news video (video time 0:18). Spectacular!
(Thanks to B/R reader Shashvat Chitransh for the suggestion here.)
After a dismal 2012 season, capped off with a Sun Bowl loss to Georgia Tech, there was an alleged all-out Trojan brawl in the locker room.
Apparently, the fighting started when some freshmen questioned the leadership of the team's seniors.
Los Angeles Daily News sources claim 10 to 15 players were involved.
In 2012, Bradley Wiggins became the first Briton to win the Tour de France and was catapulted into sports celebrity-dom.
But at least one Brit may have not been entirely happy with the win: teammate Chris Froome.
On the last mountain of the course, Froome, whose job it was to ride in front of Wiggins and help him conserve energy, apparently was tired of holding back. He zoomed up, up and away, leaving his yellow-jersey-holding team leader to fend for himself.
When ordered back, Froome obeyed. But his desire to play first fiddle became clear. And tensions crackled.
The relationship between these two titans of NASCAR does not ride a smooth asphalt track. More like a jagged, thorny stretch of the Baja 1000.
Gordon was once Johnson's mentor and idol. But when Johnson grew into a celebrated champion, tensions erupted.
Comment sections of race footage on streaming websites began to populate with snarky comments pitting the two stars against each other.
Team owner Rick Hendrick sums up their relationship this way:
"They genuinely like each other but want to beat the other guy. ... Jeff's very proud of what Jimmie's done. But seeing him go on to win five championships in a row, if that didn't bother him, he shouldn't be in a race car."
Rumor has it that a year ago, these two superstars were texting back and forth like excited high school students. Plotting. Arranging their alliance.
Then it happened: Bryant and Howard on the same team! Expectations soared. This was a match previously made only in fantasy leagues and video games. A dynamic duo.
But when it became clear that the Lakers would be no superteam, animosities rose. At least once, boiling tempers allegedly came close to a locker-room brawl.
More recently was a report that Howard has been mocking Kobe's lower-than-usual shooting stats.