4 reasons Celtics won Game 1 despite another key injury

The Boston Celtics entered Game 1 of the Eastern Conference semifinals at a severe disadvantage against the surging Philadelphia 76ers, winners of 20 of their last 21 games. Not only was Boston without the services of All-Star talents Kyrie Irving and Gordon Hayward, but one of their top scorers in Jaylen Brown was absent due to a right hamstring injury.

With a raucous crowd at TD Garden in their corner, the Celtics overcame a lack of bodies and put the hurt on the visitors with stout defense and some elite shooting, opening the series with a 117-101 victory Monday.

Here are four reasons why Boston found so much success against Philly in Game 1.

'Scary Terry' continues to blossom

Rozier's Game 7 performance to help eliminate the Milwaukee Bucks on Saturday was the strongest postseason outing of his young career. Then Monday's game happened.

The 24-year-old outdid himself to establish another new playoff career high, dropping 29 points on 18 shots in 35 minutes of action. He grabbed eight boards, dished out six assists, stole the ball twice, and drilled a scorching 7-of-9 from 3-point range - two more makes from deep than the entire Sixers roster.

Rozier's game has gained a degree of swag since he took the reins from Irving at point guard. His shooting can be highly unreliable, but on this night, Rozier showed zero hesitation with his offense. He took smart shots when the ball reached his hands, and when the defense caved in, he'd dribble out of harm's way and find an open man.

When he strutted into the building wearing a Drew Bledsoe jersey - a parting shot at Milwaukee's Eric Bledsoe - we should have known that the long ball was going to fall his way. When you're hot, you're hot, and Rozier knows he's en fuego. - Walder

Horford lived up to his All-Star billing

Remember when Boston media took to calling Horford "Average Al"? Remember when NBA fans mocked Horford's All-Star selection, assuming he must have been selected last when the captains drafted their teams? Horford has more than justified his All-Star billing. He was one of the most impactful players in the Celtics' Game 1 win - a matchup featuring two Sixers many consider generational talents.

Horford finished with 26 points on 10-of-12 shooting from the floor, seven rebounds, four assists, and just two turnovers, despite touching the ball on pretty much every Celtics possession. As is often the case with Horford, the boxscore didn't do justice to his contributions on either end of the floor.

Horford was the steady presence the Celtics needed in all phases of the game, doing yeoman's work on defense against Joel Embiid and Ben Simmons and facilitating an offense that's still functioning without Irving. When push came to shove, he didn't hesitate to put the ball in the hoop himself. With Horford shepherding Boston's young flock, the undermanned Celtics have a great chance to thwart the talented but inexperienced Sixers. - Potter

The Celtics stymied Simmons - and maintained their 3-point defense

The Celtics boasted the top defense in the regular season, and after a relatively high-scoring series against the Bucks, they appear to have found their groove again.

Crucially, the Celtics did a great job of stopping Simmons' bull-rush dribble penetration - a ferocious attack that collapses the defense, drawing weak-side defenders away from their marks on the 3-point line. The Celtics took a committee approach, using a combination of Horford's athleticism, Semi Ojeleye's fire-hydrant-like stature, and Marcus Morris' all-around abrasiveness to hold Simmons at bay. It worked; the Sixers were able to muster only three corner 3-point attempts, converting just one.

Sure, Embiid broke free for a game-high 31 points and Simmons still recorded 18 points and seven assists, but the Sixers combined to shoot just 5-of-26 from beyond the arc. For comparison, they shot 37.3 percent on an average of 30.6 attempts per game in their series against the Miami Heat. If the Sixers can't find their outside rhythm against a gritty Celtics defense, they're in trouble. - Potter

Philly's defense was shambolic

With Brown joining Irving and Hayward on the injured list for Game 1, the Celtics figured to have a miserable time trying to scratch out points against an elite Sixers defense. Instead, they put up a 119 offensive rating while shooting 17-of-36 from 3-point range. Part of that was a result of unsustainably hot Celtics shooting, but Philadelphia helped them out with uncharacteristically sloppy defense coupled with an incoherent game plan at that end of the floor.

The Sixers allowed J.J. Redick and Marco Belinelli to get roasted by Jayson Tatum, while leaving Simmons - a better on-ball than off-ball defender - to play free safety while ostensibly checking Marcus Smart. It didn't work. They miscommunicated on pick-and-pops, leaving Horford wide open while two defenders chased the ball. They overreacted to drives and overhelped in the post (you probably don't need to double Morris!), which played right into Boston's hands. Much of it stemmed from breakdowns at the point of attack, but the Sixers rarely managed to recover once they got themselves into rotations, leading to a barrage of open threes.

Philadelphia's greatest defensive strength is having Embiid as a gigantic deterrent at the rim. The Celtics used Horford to pull Embiid away from the basket, but for the most part, they didn't bother challenging him - instead driving to pass (knowing the Sixers would cheat and leave someone open) and relying on their perimeter ball movement to break Philly down. That's how Boston dominated offensively while attempting just 19 shots in the restricted area. - Wolfond

(Photos courtesy: Action Images)