Head coach Spoelstra missed Saturday's 110-95 loss to the Brooklyn Nets for personal reasons, with assistant coach Chris Quinn filling in.
However, Miami confirmed that the 60-year-old was back with the team for the meeting with the Kings at FTX Arena.
Ahead of Monday's game, the Heat (47-28) had the second-best record in the Eastern Conference but sat below the Boston Celtics. The Milwaukee Bucks and the Philadelphia 76ers were half a game back in a tight top four.
Ultimately, that change would be Markieff Morris and Victor Oladipo falling out of the rotation entirely, playing zero combined minutes.
The Heat looked great with their new line-ups, which featured Max Strus slotting into a starting role, winning each of the first three quarters comfortably on the way to a 123-100 victory.
Speaking to post-game media, Spoelstra made a point of protecting his benched players' feelings, and stressed that more tinkering would be ahead.
"These are tough decisions, and there are a lot of different things that could work, but we just felt like at this particular time that these moves may clean up some things with the rotation," he said.
"Those aren't easy decisions, and I think we all just have to have empathy and grace for some of these changes for the guys that didn't necessarily play tonight.
"It's about understanding that we have a roster full of proven, capable guys, and we're going to need everybody, particularly in this final push and in the playoffs.
"A lot of it will be matchup-based… we'll just keep an open mind about what we may need to do moving forward."
Spoelstra went on to say that the difference in this game was about far more than simply benching two solid players.
"This wasn't a 'one move' thing – we were very disappointed about the past four games, and this has been trending, really, even before that, when we were winning," he said.
"It's not an indictment on anybody – sometimes these things can be chemistry things, sometimes it's just the flow of certain guys playing off of each other.
"The ball and body movement was better – less holding [the ball], we're moving the ball, guys were able to play to their strengths. It was less stagnant for sure.
"We've seen what Jimmy [Butler] can do when he has open spaces to be able to be creative, and be able to attack, and be able to make plays. I know he hit three three-pointers tonight – I love that – but he was in a lot of places where he can be successful and effective.
"There were a lot of different layers to [today's moves] – again, it's just one game. Our roster is deep, and our roster checks a lot of different boxes, which we feel you need in the playoffs.
"Each series – if we're fortunate enough to play multiple series – they have totally different needs and complexions, and we feel like versatility and our depth is really one of the greatest strengths of this team."
Miami regained the Eastern Conference one seed with the result, but it will switch hands once again if they cannot defeat the surging Boston Celtics on Wednesday.
Miami confirmed prior to tip-off that Spoelstra would not be in attendance at FTX Arena due to personal reasons.
Assistant coach Chris Quinn was handed the reins of the Heat, who sat top of the Eastern Conference with eight games to play.
Miami have lost their past three games, opening the door for the Philadelphia 76ers to displace them as the top seed in the closing stretch of the regular season.
The Nets sat eighth in the East and looked set to be heading for the play-in tournament.
The Celtics rallied for a 121-108 victory over Miami on Friday to cut the Heat's Eastern Conference finals lead to 3-2.
But Boston struggled early, trailing by 12 points, before a 41-25 third quarter helped them turn the game.
Celtics head coach Stevens said improvement defensively was key for Boston.
"I just thought we played with great tenacity defensively, and our offense followed suit," he told a news conference.
"But they're very hard. It's easy for me to sit up and say to be at our very best and get stops on every possession.
"This is a heck of an offensive team, a heck of a well-coached team and hard to guard."
Celtics star Jayson Tatum scored 17 of his 31 points in the third quarter, with Boston going on a 20-3 run.
Miami head coach Erik Spoelstra lamented his side's inability to slow the Celtics down.
"We missed some open shots to start the quarter and then those turned into run-outs that got them going, those easy ones. This is a team that has great offensive firepower," he said.
"When they see the ball go in the basket they started to get more aggressive and putting a ton of pressure on us in the paint, much like they did in Game 3 and we weren't able to shut that off, and they just carried that through."
Game 6 is on Sunday.
The return of Defensive Player of the Year Marcus Smart from a foot injury ignited the Celtics on the offensive end just as much as defensively, with the team hitting a red-hot 20-of-40 from three-point range.
Boston's five that played at least 30 minutes – Jayson Tatum, Jaylen Brown, Grant Williams, Al Horford and Smart – shot 17-of-29 from long-range, and combined for 23 assists, which was two more than Miami had as a team.
Speaking to post-game media, Butler said the Celtics "tried to embarrass us", but pointed out that they were always going to be facing an uphill battle against such an outlier shooting performance.
"You do have to move on, but I don't like to move on from this. It has to hurt," he said.
"They tried to embarrass us – they did embarrass us. I think we got to realise that, or use it as fuel, but realise that the game can get out of hand when you're playing against a really good team like them that can score the ball and get stops.
"They made shots that they missed last game. That's just what it is.
"It's going to be hard to beat anybody when they shoot 50 per cent from the field and 50 per cent from three. They were the more physical team overall, and they got one on the road.
"Overall, we just have to be better. We've got a tough job to do to go over there and win, but if they did it, we can do it as well."
He added: "I look at it as 'it can't get too much worse'. They whipped our tail on our home floor.
"I guess if they do it on their home floor it's supposed to happen, but I don't see us doing that again.
"The first half has been brutal for us in both of these games, we just got to come out and play harder from the jump and be ready, because they be throwing some haymakers in the first half."
Heat coach Erik Spoelstra said he did not feel like his side played poorly – but that it felt like the Celtics wanted revenge for Game 1.
"You definitely have to credit Boston," he said. "It's not just that they came in with great urgency and physicality – they did have that, for sure – they also played well. They played really well on both ends.
"We know what they're capable of defensively – they've done this to some very good offenses. I'm sure they were not happy with us putting up 118 in Game 1, and they came out very disruptive.
"They got us out of our normal rhythm and flow, and the shot-making on the other end was very tough to overcome.
"You get to this point – in the Conference Finals – you just have very good teams. Teams without many weaknesses, it's great competition.
"This only counts as one, and that's what the experiences players and staff in the locker room understand. We don't like it, but they played extremely well."
The new deal will pay Kerr, who has guided the Warriors to four NBA championships, $17.5 million a year.
His current deal was set to expire at the end of this season.
San Antonio Spurs coach Gregg Popovich makes more annually, according to sources, but he also serves as the team’s president. Miami Heat coach Erik Spoelstra signed an eight-year extension that pays him approximately $15 million a season.
Kerr, 58, is in his 10th season as coach of the Warriors and holds a career regular season record of 501-264 and is 99-41 in the playoffs. He won his 500th game last week to become the fifth-fastest coach to do so in history.
Coach Spoelstra and six-time All-Star Butler, along with Udonis Haslem on the Heat bench, appeared to exchange fiery words and gestures during a timeout as the Heat struggled against the Golden State Warriors.
Golden State bolted to a 69-50 lead after scoring the first 19 points of the third quarter, and amid this slide came the dispute within the Heat ranks.
Spoelstra slammed a clipboard down onto the court and confronted Butler before others attempted to separate the pair.
Allowing himself to joke after the game, which saw the Heat roar back to establish an 84-81 lead before crumpling to a 118-104 defeat, Spoelstra explained the incident.
"Everybody was wondering where the dinner plans were tonight after the game," he said, before answering more seriously.
"It was pretty clear, we have a very competitive, gnarly group, and we were getting our a***s kicked, and it's two straight games we were not playing to the level we wanted to play.
"Every person in that huddle was pretty animated about our disappointment at how we were playing."
This game followed a 113-106 loss to the Philadelphia 76ers, and the Eastern Conference-leading Heat's record now stands at 47-26.
Asked about whether the public bickering could have a lasting impact, Spoelstra said: "It won't, we have bigger things to accomplish, but we do want to play better, and everything has to be better across the board.
"It starts with our leadership, our veteran players have to lead, and then we just have to play better, play better to our identity and that's really all the discussions were.
"I know how it can look from the outside, but that is more our language than playing without passion or without toughness, or without multiple efforts and lifelessness.
"Everything that happened in the hall from then on, as we cut that 19-point lead, that's way more to our personality."
Spoelstra even hinted the flash point could have a positive impact.
"You can use moments during a season to catapult you. You can galvanise together over frustration and disappointment," he said. "Teams can also go the other way. I don't see that with our group. But we have needed a kick in the butt from these two games.
"These two games were disappointing to everybody. You see a competitive group that is not playing to the level or the standards we want to play at.
"Let's give credit to Golden State. We played with great passion to get back into the game, but they executed well, and they made some big shots."
Boasting a 96-87 lead midway through the fourth quarter at TD Garden on Friday, the Celtics looked set to level the series at 1-1, only for Butler to lead his team to a huge 111-105 victory.
Butler scored nine of his team-high 27 points after he went head-to-head with Williams in a heated exchange in the fourth quarter, with the Heat closing the game with a 24-9 run.
Asked whether that incident helped to instigate his strong finish to the game, Butler said: "Yes, it did.
"But that's just competition at its finest. He hit a big shot, started talking to me. I like that. I'm all for that.
"It makes me key in a lot more, it pushes that will that I have to win a lot more. It makes me smile. It does.
"When people talk to me, I'm like, 'okay, I know I'm a decent player if you want to talk to me, out of everybody that you can talk to'. It's just competition.
"I do respect him, though. He's a big part of what they try to do. He switches, he can shoot the ball. I just don't know if I'm the best person to talk to."
Heat guard Caleb Martin concurred, suggesting Williams picked the wrong man to provoke.
"I knew it was going to be good for us," Martin said. "Knowing Jimmy, at that point in the game, if you get him going… we'll take mad Jimmy any time!
"You could kind of see it in his eyes that he was ready to go after that."
With Miami set to assume home advantage for Game 3 on Sunday, head coach Erik Spoelstra said the Heat's ability to find new ways to win has been a key feature of their postseason run.
"It feels like this has just been our existence all year long," Spoelstra said. "I guess nobody is really paying attention.
"But every single game… it felt like for weeks on end, every game was ending on the last-second shot, whether we're shooting it or the other team is shooting it.
"You develop some grit from that. Whether that turns into confidence or not, sometimes you don't have the confidence, but at least you have that experience of going through stuff and you understand how tough it is."
A 102-82 loss in Boston on Monday night came on the back of Miami scoring a trifling 11 points in the first quarter, with Jimmy Butler scoring just six points all night and no Heat starter reaching double figures.
The visitors shot just 33.3 per cent from the field (30 of 90), with Boston's win squaring the series at 2-2 and setting up Game 5 in Miami on Wednesday evening as a pivotal occasion.
Coach Spoelstra said: "More than anything, our offense really hurt us at the beginning. They weren't getting the sort of purposeful execution that you need to on the road. [Boston] were able to get some relief points from that and get to the free-throw line. They did a better job of getting into us and rotating guys into the paint."
It was 57-33 by the halfway mark, and Spoelstra admitted the Heat simply failed to ignite. Yet he says Miami can swiftly set the game aside and dominate the next time the teams meet on court, saying it would not surprise him if the tables are turned.
"We've got guys that love these kinds of moments, the playoffs. You've just got to stay together," Spoelstra said.
"This is part of the playoffs. There are these extreme highs and lows, a lot of emotion. You just have to stay the course, stay together. What you're looking at is a great series. It's 2-2. You have to embrace that. Hopefully this competition beings out the absolute best in all of us.
"They got the best of us tonight. We'll take this hit and then get to Miami and get ready for Game 5. Whatever they have done to us, we can do to them."
Jayson Tatum led Boston with 31 points. The Celtics led by 32 points at one stage before Miami began to claw back the deficit late on.
"We're not making any excuses. They outplayed us tonight, for sure," said Spoelstra.
