BOSTON -- During the offseason, the expectation wasn't for 37-year-old Al Horford to be making postseason starts for the Celtics. But in staying ready and prepared for all circumstances, the 17-year veteran stepped up like a leader.

Returning home for a series-clincher in Game 5 against the Cavaliers, Boston knew it needed to lean on Horford again. Kristaps Porzingis remained sidelined, supporting from the bench, therefore, Horford, who'd been playing a sixth man's role all season long, needed to infuse his second-unit leadership into the starting lineup. From tip-off, it was clear Horford understood that.

"Everyone leads in different ways and Al's not as vocal as he is inspirational," Celtics head coach Joe Mazzulla said after Boston's 113-98 Game 5 victory. "So when he plays the way he does it's contagious. Everybody has different ways in which they lead, and you saw Al, the gifts in which God gave him, and his ability to impact people around him. He did it at a high, high level today, but he does it all the time instrumentally."

Horford helped set the tone early, not just for the Celtics, but for all fans in attendance at TD Garden on Wednesday night. After a mundane 28-28 finish to the first quarter, it was clear the energy wasn't there, which in the past, backfired on the Celtics -- Horford knows this from experience. So he did everything to go the extra mile while on the floor.

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Before going into halftime, Horford stunned everyone by tracking a ball heading out of bounds and spiking it off Cleveland's Dean Wade to gift Boston with an extra possession. Celtics fans showed appreciation, getting significantly louder and more energetic in watching Horford's hustle on display at the perfect time.

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"The one play in particular when he saved the ball out of bounds in the last two minutes of the second quarter, it just gave us that extra possession and pumped the crowd up, pumped our team up," Jayson Tatum said. "Those plays, that was so meaningful and just how he played in the second half on the defensive end. He knocked down big shots time and time again. His performance, his energy, his leadership tonight was crucial."

Whether on offense, defense, or in the sideline huddles during timeouts, Horford left nothing to chance. He wasn't interested in taking another flight to Cleveland for a Game 6, and it showed in every second of Horford's 35 minutes on the court.

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Horford scored 22 points on 8-of-15 shooting, grabbed a game-high 15 rebounds, and finished with five assists and three blocks, becoming the third 37-plus-year-old in NBA history to score 22-plus with 15-plus rebounds and five-plus assists -- joining LeBron James and Kareem Abdul-Jabbar, according to Jared Weiss of The Athletic.

"Once we got going and the game got going, I just saw that we weren't where we needed to be as a group," Horford said. "And it's like, you have to do something and I just want to bring that energy to our group and the group was able to feed off it. And we all just continued to play, the guys continue to trust me because the way that they were designing everything was for me to shoot the ball and running plays through me."

Boston now has its spot in the conference finals -- either against the Knicks or Pacers -- along with bonus rest and another chance at the NBA Finals.

Featured image via David Butler II/USA TODAY Sports Images