"He had a terrific game," Houston coach Mike D'Antoni said. "I could use the exact same words I told you last time about him. He's just doing it again."
It was the sixth 50-point performance of the season for Harden, the lone NBA player to hit the milestone more than once in 2018-19, and the 15th of his career. Only Wilt Chamberlain, Michael Jordan, Kobe Bryant and Elgin Baylor have scored 50 points more times in NBA history.
It was also the seventh time that Harden dished out at least 10 assists in a 50-point performance, a feat no other player has accomplished more than three times.
Harden fell only three points shy of matching his career high and the franchise-record 61 he scored in a Jan. 23 win over the New York Knicks.
"I wasn't really paying attention to that," Harden said. "I was worried about getting stops, trying to play my butt off and create some energy in the building."
Harden pointed to the Rockets' defensive turnaround in the second half as the primary reason they were able to rally from a 21-point deficit. Houston held Miami to 20 points in the fourth quarter, when Harden generated 22 points, scoring 17 and feeding Austin Rivers for a 3-pointer and Clint Capela for a layup.
D'Antoni declared it a "gut check" victory for the short-handed Rockets, who were without injured rotation players Eric Gordon, Kenneth Faried and Iman Shumpert while power forward PJ Tucker was ejected after picking up two technical fouls while arguing an illegal screen call against him late in the third quarter.
"This is a character win," D'Antoni said. "When you get in the playoffs, that's what counts -- character and brains. And we had both of them tonight."
The Rockets also had the reigning MVP snap out of a relative mini-slump, making a massive comeback possible.
Harden had averaged a subpar-by-his-standards 29.3 points in three games since the All-Star break. He sat out Saturday's win over the Golden State Warriors because of a cervical strain that he suffered during Houston's Feb. 20 practice, a nagging injury that prevented him from following his normal between-games routine and interrupted the remarkable rhythm he established during his streak of 32 consecutive 30-point games. He shot only 37.8 percent from the field in his first three games after the break, including 3-of-31 from 3-point range.
But Harden efficiently picked apart the Heat, staying aggressive against a zone defense Miami frequently used to try to slow him down. He was 16-of-32 from the field, 8-of-18 from 3-point range and 18-of-18 from the free throw line.
"I don't worry about missing shots or making shots," Harden said. "I worry about taking the shots that I work on, and they're going to go in eventually. Whether I shoot 2-for-30 or 15-, 16-for-30, those shots are going to get shot."
Rivers said the Rockets were surprised to see that Harden had scored 58 when they scanned the box score because his points all came in the flow of the game.
"He did it naturally tonight, which I loved," said Rivers, who had 17 points and two assists off the bench. "He didn't force anything. James just naturally scored 58. He knew that we needed a burst, guys were down. He just did an incredible job."
It was Harden's free throw total that pained Miami's Dwyane Wade, who had 12 points on 6-of-15 shooting in the final game of his career against the Rockets. Wade, who swapped jerseys with longtime friend Chris Paul at midcourt after the game, said not reaching against Harden was a point of emphasis in the Heat's game plan that they failed to execute.
"He's definitely one of the most unguardable players this game has ever seen," Wade said. "But a lot of mistakes of putting that hand in that cookie jar. It's something we talked about and something we knew we couldn't do, and we did it a lot."
The Rockets recorded their fourth consecutive win to improve to 37-25, a game and a half behind the Oklahoma City Thunder and Portland Trail Blazers, who are tied for third place in the Western Conference standings. Houston is 17-6 this season when Harden scores at least 40 points, which he has done more than three times as often as any other player.
"James was unbelievable," said Paul, who had 14 points, 6 rebounds and 4 assists and made several key plays down the stretch to seal the win. "We're just trying to find ways to win. Nobody's keeping track of shots and all that stuff. It's just win. That's what James always says: 'We need one in that left column.'"