The Kansas City Chiefs pulled off the greatest second-half comeback in franchise history on Sunday afternoon at Arrowhead Stadium by beating the San Diego Chargers by a score of 33-27.

Trailing 27-10 with a little more than 9 minutes remaining in the game, the Chiefs scored 17 unanswered points to force the game into overtime, ultimately sealing the game with an Alex Smith touchdown run on the opening drive of overtime.

To put it simply, it was a game to remember.

Here are 10 observations from Sunday:

1. We should have learned last year not to count this team out

There are going to be some obvious parallels drawn between last year's team, which overcame a 1-5 start to the season to win a franchise-record 11 straight games (including the team's first playoff win in more than two decades) and the game on Sunday.

But first, it has to be said—it's a new year, a new team, but there's just something about the way these guys rally around their even-keeled, level-headed leader, Andy Reid.

Reid refuses to be swayed by the emotional roller coaster that is often associated with an NFL game, particularly one as exciting as what we all saw on Sunday.

When players were asked in the locker room after the game as to what's behind their ability to stay within themselves and claw their way back when their backs are against the wall—almost to a tee—the players will point in the direction of Reid.

"We have enough guys who were a part of last year's team that understand nothing's impossible," Reid said after the game. "Then you have an influx of these new players, so they've got to learn, and it took a good half to figure it out. They know now—right?

"They didn't experience it last year, so they understand it now. You got a full team that has that feeling."

2. Spencer Ware was the spark for the Chiefs on Sunday

If you're looking for one individual player who can be credited with sparking the team to this historic comeback, that player is running back Spencer Ware.

When you look Ware's stat line—11 rushes for 70 yards and a touchdown to go along with 7 receptions for 129 yards—both of which led the team, there's an obvious reason he was a big part of the team's success, but it was the way in which he gained those yards that brought energy to the Chiefs sideline when it was needed the most.

Ware broke through tackles on almost every touch, particularly in the second half, which not only got the crowd going and on its feet, but it also fired up his teammates.

With veteran Jamaal Charles inactive on Sunday, Ware saw the majority of action in the backfield for the Chiefs offense, and from the beginning—you knew he was going to be a big part of the plan.

Ware touched the ball on three of the first six Chiefs offensive plays, and the longest play of that first drive was a 28-yard reception on first-and-10 from the San Diego 37-yard line.

It was that reception that set up Cairo Santos' 47-yard field goal, which gave the Chiefs an early 3-0 lead just a few minutes into the game. They wouldn't score again until Maclin's touchdown with a little more than 9 minutes remaining in regulation.

Of the 199 total yards Ware had on the day, 141 of them came in the second half.

3. Alex Smith's second half shows why he's leading this team

Through the first 38:58 of Sunday's game, quarterback Alex Smith hadn't had the kind of game that all of us who have watched him throughout OTAs, minicamp, training camp and the preseason, would have expected.

He was 10 of 16 for just 101 yards and the offense had punted on five straight possessions after that opening field goal, including a couple of three-and-outs.

Then, on the seventh offensive drive, Smith found Ware down the middle of the field for 45 yards on first-and-10 from the Chargers 25-yard line. It was the longest play of the day for the Chiefs offense.

That play seemed to change everything, because in the final 26:09 of the game, Smith was the guy we expected him to be from the beginning, completing 24 of 32 passes for 262 yards and 2 touchdowns, including the game-winning touchdown run on a speed-option from the 2-yard line on third down.

Smith had a few gutsy throws down the stretch to guys who weren't necessarily open, but he trusted them to make plays—like Jeremy Maclin's 27-yard reception across the middle that proved to be one of the most important plays of the game.

Smith trusted Maclin to make a play, as he released the ball deep down the middle and to Maclin's credit—knowing he was going to take a shot—went up across the middle and came down with the ball, taking a big hit in the process. Maclin has often said that he's accountable to his teammates when the ball is in the air, and his clutch reception in knowing he was going to take a shot only further displays the reason the other players on the team look up to him.

Smith's 15-yard pass to Kelce near the goal line in overtime on the far left sideline is another example of Smith trusting his guys to make plays and cutting it loose a little bit. He was playing to win the game.

4. Philip Rivers' impressive third-down conversion sets up Chargers first touchdown

When Chiefs defensive coordinator Bob Sutton spoke with the media earlier this week, there was no doubt as to the awareness of Rivers' ability to move around the pocket.

"He's really an outstanding player who moves in the pocket better than people realize," Sutton explained. "His ability to scramble in the pocket to make throws is the real deal."

Rivers displayed this ability on the Chargers first offensive drive when he converted a third down by throwing across his body across the middle of the field on third-and-6. After avoiding the pressure up the middle by sliding in the pocket, Rivers found Tyrell Williams for 33 yards.

Just two plays later, running back Melvin Gordon ran it in from 1 yard out to give the Chargers the early 7-0 lead after the extra point was good.

Rivers finished the game 25 of 36 for 243 yards and a touchdown, but it was a different offense after his star receiver—Keenan Allen—left the game late in the first half.

5. Keenan Allen leaves with knee injury

After grabbing 6 catches for 63 yards through the first 28 minutes of the game, Allen, who missed eight games last year with a lacerated kidney, went down with a non-contact knee injury and did not return.

Allen quickly raised his hand to call the trainers over after he went to the ground. He was visibly emotional as he was being carted off the field right before halftime.

Rivers was 15 of 17 for 143 yards before Allen's injury, and the Chargers offense as a whole had scored on all three of their drives with him in the game, including converting 6 of 6 third downs.

After Allen's departure, Rivers went 10 of 19 for 100 yards, converted 1 of 9 third downs and had 3 field goal attempts (1 missed) and 5 punts on the final 8 offensive drives.

6. Tyreek Hill grabs first NFL touchdown

Late in the third quarter and with the Chiefs trailing 24-3, rookie receiver Tyreek Hill took the quick screen to the outside on second-and-7 and broke a tackle on his way to the end zone.

Hill, whose speed has been talked about all offseason, was put on display as he accelerated through the defense and into the end zone.

It was the beginning of the comeback.

7. Dee Ford steps up in a big situation

With the game tied and with less than a minute remaining in regulation, and Rivers having just completed a 12-yard pass to Danny Woodhead to get the Chargers closer to scoring range, the Chargers were just 28 yards or so away from a legitimate game-winning 52-yard field goal attempt, third-year outside linebacker Dee Ford made one of the key defensive plays of the game.

Ford got around the edge and sacked Rivers for a loss of 10 yards on first down, destroying any real chance for the Chargers to get into any kind of scoring position. The Chargers would run the ball on second and third down, basically settling for overtime.

The defense wouldn't step on the field again as the Chiefs scored on the opening drive of overtime.

8. Justin March leads team in tackles

In the first start of his career and the first regular-season action of his career, second-year linebacker Justin March led the Chiefs in tackles with 9 on the day, holding down the starting position next to Derrick Johnson on the inside.

9. Chiefs thrive in scoring position

One of the most important stats for an offense at the end of the day is their success when they get close to the end zone, and the Chiefs succeeded in that area.

While they weren't playing well enough early in the game to get near the end zone as they punted on five of their first six offensive drives, they came through when they got close enough to strike.

The Chiefs finished 4 of 5 in red zone efficiency and were 2 of 2 in goal-to-go situations, while the Chargers finished 3 of 5 in red zone efficiency.

One play worth noting in this area came from veteran safety Ron Parker, who knocked away the third-and-9 pass attempt from Rivers to receiver Tyrell Williams in the corner of the end zone midway through the third quarter, which forced the Chargers to settle for a 29-yard field goal.

Parker's play saved 4 points, which would have made all the difference late in the game.

Most people will remember the plays at the end of the game, which ultimately won the game, but the plays made late in the third quarter and into the early parts of the fourth quarter were just as important.

10. Jeremy Maclin leaves game briefly, returns after going through concussion protocol

After taking a hit across the middle on a 22-yard reception with just over a minute left in regulation, a play that turned out to be one of the most important of the game, Maclin left briefly and had to go through the NFL's concussion protocol. Chargers safety Jahleel Addae was flagged for unnecessary roughness on the play.

"[Maclin] had to go through the protocol – was okay and came back," Reid explained after the game.

Maclin finished the game with 5 receptions for 63 yards, all of which came before that fourth-quarter grab.

• Bonus observation - the Chiefs have now won six-straight games against the AFC West, including five-straight against Chargers' quarterback Philip Rivers.