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The Los Angeles Lakers did the improbable against the visiting Boston Celtics Tuesday night amid a set of circumstances that were nearly impossible -- all before walking away with an outcome that felt, well, inevitable.

Trailing 81-61 in the third quarter against, not only their hated arch-rivals, but the best team in the NBA this season, the Lakers mounted a staggering 45-12 run over the next 15 minutes to take a a 13-point lead into the final minutes of regulation. It was the single most impressive stretch of basketball the Lakers played all season, and should serve as a catalyst for them as the Dec. 15 trade restrictions are set to lift on Thursday and--

Wait ... the game didn't end there? ... Boston did what?

The Celtics made that 13-point lead vanish over the next 3:44, and closed the game with a 17-4 run to send this surprise classic to overtime, where they secured their league-leading 22nd victory of the season and sent the Lakers home with perhaps their most crushing loss of the season.

So how did it happen? How did the Lakers blow a 13-point lead in under four minutes after spending the previous 15 minutes beating the stuffing out of the Celtics? Let's embark on a tale of poor shot-selection, lazy closeouts and some of the sloppiest basketball you will ever see.

Our story picks up with a missed LeBron James 3-pointer. Anthony Davis and Grant Williams were fighting for position on the rebound, but Jayson Tatum ultimately pulled it in. Williams ran the floor much harder than Davis, so when Tatum found Williams wide open behind the arc, Davis only offered a halfhearted step in his direction as Boston's big man cut the lead to 10.

Normally, there would be another clip to follow, but what Marcus Smart did happened so quickly that the television cameras barely caught but a glimpse of it. Somehow, he managed to steal the weak inbound pass and make a layup all while the camera remained fixed on Williams after his jumper. A 10-point lead was suddenly down to eight. It's a trick the Lakers shouldn't be falling for, given that Alex Caruso used to do it for them all of the time.

Three-point attempts are never a given, of course, but this three-play sequence -- the Lakers' missed 3 and the Celtics' two quick buckets -- was a potential eight-point swing. L.A. could have been up 109-93, but instead only lead 106-98.

What follows is a quote that would inform Boston's defense for the rest of the night. "All they have is transition and the paint," Celtics coach Joe Mazzulla was caught saying on a wired for sound segment of TNT's broadcast. The Lakers spent most of the final minutes settling for long or midrange jumpers. This elbow miss is a Russell Westbrook staple.

The stars for both sides traded buckets from there. Two free throws for Tatum. A turnaround jumper for Davis. A Tatum 3-pointer. A James mid-range jumper. That last LeBron bucket turned out to be the final two points the Lakers would score in regulation. The team as a whole failed to get back on defense afterward, allowing Smart to go at Austin Reaves with a full head of steam knowing he'd have no help at the rim. Two points on the layup. It's now a five-point game.

The Lakers did catch a bit of a break when Davis fell out of the play after missing a jumper, but Williams couldn't convert on the wide-open 3-pointer he got as a result. James walked the ball back up the floor and got fouled as he attempted to call a timeout. When the Lakers took the ball out of bounds, James frittered away most of the 15 seconds he had remaining on the shot-clock in attempting to get Tatum switched off of him in favor of Williams. It worked, but not until the shot-clock has been bled to under five seconds. And after Williams denied his first drive, James had no choice but to jack up a desperation a 3-pointer.

This has been a problem for the Lakers and James for quite some time. They get into their offense far too slowly, and James, when he hunts switches, has a tendency to play with his food before he eats it. If James was going to have time to attack the basket, it needed to come immediately off of the screen. But he doesn't, and the clock gives him no other choice but to shoot. The miss would become the defensive possession that swung the game in Boston's favor.

Jaylen Brown would take the ball down the court, and James, directing traffic as the Lakers scurried back on defense, found himself on Smart. Smart seemed to jog toward Brown intending to screen Davis off of him, but at the last moment, he retreated back out behind the 3-point line. James stayed perfectly still. Nobody rotated. Smart made the wide open 3-point shot. It's now a two-point game.

Charitably, we can say that James expected Smart to set the screen, which would have forced him to pick up Brown. But he made no effort to recover back onto Smart. Troy Brown Jr. could have rotated onto Smart, which would have forced Russell Westbrook into the corner and set up Luke Kornet for a dunk or layup. That's hardly ideal, but with two passes still needed, maybe James could have scrambled down to the paint. Even if he couldn't have, given up two points would have been better than yielding three.

The Lakers are granted a slight reprieve when Luke Kornet fouled Davis with 28 seconds remaining. You might have figured if he makes both the game is probably safe. Heck, hit one and Boston has to play for a 3-pointer. But Davis missed both.

This is becoming a real problem for the Lakers. After overcoming a nine-point deficit with 30 seconds to play against the Sixers on Friday in Philadelphia, Davis missed what would have been the game-winning free throw and the Lakers lost in overtime. With 43.6 seconds left in a one-point November loss to the Indiana Pacers, Davis missed a free throw that would have given the Lakers enough of a cushion to at least go to overtime after Andrew Nembhard's buzzer-beater. Three winnable games lost in part because an 83 percent free-throw shooter keeps missing the biggest ones he takes.

It's befuddling until you look at the box score. Davis played 37 minutes in that Pacers game. He played 36 in Philadelphia despite having the flu. On Tuesday, he played 41 minutes in regulation and all five minutes of overtime. He's playing all of these minutes at center, a position he's known to dislike because of the toll it takes on his body. It's possible that Davis is simply out of gas by the time crunch time arrives. With no other viable big men to protect him, Darvin Ham has no alternative.

The same goes for James. He and Davis combined to take 49 of the team's 93 field goals against Boston. They expended more energy than could be reasonably expected of them during the comeback. James played the last 18:57 seconds of regulation and overtime while sitting for only about two or three in the third quarter. Davis played the entire second half and overtime with no breather.

By this point, the outcome is relatively predictable. Tatum got James one-on-one and beat him with a turnaround jumper. Tie game.

The exhausted James ran down the clock and settled for another ugly 3-pointer as time expired. The miss sent the game to overtime, where the Lakers were outscored 12-8.

When they led 106-93, ESPN's Win Probability chart gave the Lakers a 99.2 percent chance at victory. It takes a perfect storm to lose such a game. The Lakers were sloppy, exhausted and downright unlucky down the stretch of this game. They could've gotten away with one of these ills. They might've even escaped with two of them. But put all three together and the Lakers managed to turn what should've been their best win of the season into what will likely go down as their most gut-wrenching loss.