CLEVELAND — MVP contender Joel Embiid started the Sixers’ game against the Cavaliers Wednesday night after being listed as questionable to play with back soreness earlier in the day.

Embiid, who was also celebrating his 28th birthday Wednesday, was present at shootaround and had a wrap around his back. When asked prior to the team session if any players would rest for that night’s game against the Cavaliers, coach Doc Rivers said, “I don’t think so.”

So far, this has been Embiid’s most durable season. The NBA’s leading scorer (29.9 points per game) has not missed a game since Jan. 31 vs. Memphis (planned rest), but subbed himself out midway through the first quarter of Monday’s home loss to Denver after playing 41 minutes during an overtime win at Orlando the previous night.

Embiid also sat out a Dec. 13 loss at Memphis with rib soreness, rested during a Nov. 1 home win against Portland and missed nine games with COVID-19 in November. He played through an early-season knee injury and, more recently, a hand issue.

The 41-26 Sixers are in the midst of playing six games in nine days, including two back-to-back sets, while fighting for playoff positioning during the regular season’s final three-plus weeks. They entered Wednesday in third place in the Eastern Conference standings, while the 39-29 Cavaliers were in sixth place. Cleveland’s All-Star big man Jarrett Allen remained out with a broken finger.

After Wednesday’s game, the Sixers host the Dallas Mavericks (fifth in the West) on Friday, the Toronto Raptors (seventh in the East) on Sunday and the Miami Heat (first in the East) on Monday.

Rivers said the data from the training staff — not the opponent — will dictate when players rest during the final three-plus weeks of the regular season.

“If [it’s] a guy’s time to get rest, he’s going to get rest,” Rivers said. “We’re not going to go by the games. We’re going to go by what the numbers tell us to do.”

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James Harden, who was nursing a hamstring injury when he was traded to the Sixers on Feb. 10, did not play until after the All-Star break and then sat out the second night of a back-to-back at Miami on March 5. Rivers said last weekend that second-year guard Tyrese Maxey would also likely get time off down the stretch.

Sixers prank Embiid on birthday

The Sixers walked into Wednesday’s shootaround at Rocket Mortgage Fieldhouse wearing similar attire.

Not team gear, but a white T-shirt featuring a giant, hilarious photo of Embiid’s face from his college days.

It was part of a team-wide prank on the big man’s 28th birthday. Teammate Georges Niang got the shirts from “Johnny ShirtFaced” (real name: Johnny Wolfe), who has created viral moments for about two years by providing professional athletes with shirts with funny photos of their teammates’ faces to wear in highly visible settings. Most notably, the Los Angeles Rams’ Matthew Stafford and Andrew Whitworth wore shirts featuring Super Bowl MVP Cooper Kupp during last month’s championship parade.

Later, the Sixers gathered in a huddle to serenade Embiid with a rendition of Stevie Wonder’s “Happy Birthday.”

Transition defense remains a focus

The Sixers have struggled with transition defense all season, entering Wednesday ranked 28th in the NBA in fastbreak points allowed (14.5 per game). That weakness had gotten worse over their past five games (20.6 per game, last in the league) before Wednesday’s game in Cleveland, and even more dreadful when that snapshot is reduced to their most recent three games in their three games (25.3 points per game, also last in the league).

“We’ve just been lazy, and teams are taking advantage of that,” Embiid said after his team allowed 29 fast-break points against Denver. “So at least the next 10 games, that has to be the focus ... we’ve just got to start being better on that end.”

When asked how to fix those woes, Embiid half-joked that “maybe we should not crash the boards and we should just all get back on defense.” Maxey added that he and teammates need to be more aware of when he or Harden drives into the paint, and the designated “get-back guys” might shift as a result.

Rivers said that was a point of emphasis in film work during the past two days.

“[It’s about] getting back, getting loaded, being more disciplined,” Rivers said. “It’s disappointing, I can tell you that, because it’s a recurring thing. I think Kevin Durant said after [the Sixers’ blowout loss to Brooklyn], ‘You know they don’t get back.’ Orlando, they made a concerted [effort]. You could just see them doing it.”

Cavaliers becoming a familiar foe

The Sixers’ first of four regular-season meetings against Cleveland did not arrive until Feb. 12. That means, to Rivers, “it feels like they’re our weekly opponent” heading into Wednesday’s Round 3.

Though the Sixers won the first two meetings in Philly, Rivers has been impressed with the Cavaliers’ sharp ascension as a young team anchored by All-Stars Allen and Darius Garland, along with Rookie of the Year front-runner Evan Mobley. After Wednesday, they will play for the final time in the regular season on April 3 in Cleveland.

“[What] jumps off at you is how much they get along and want to play together and get it right,” Rivers said. “That comes from coaching and that comes from young guys also just buying in. They know who their star is in Garland. That’s also unusual with a young team. Usually all the young guys are trying to fight, ‘Well, I’m the star.’

“There’s no doubt who the star, who the guy, is on this team, and that is going to allow them to have a long run as a good basketball team.”

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The newfound familiarity with the Cavaliers could extend into mid-April. If the playoffs began Wednesday, the Cavaliers would be the Sixers’ first-round playoff opponent. Cavs coach J.B. Bickerstaff said it is too early to entertain the possibility of a postseason series.

“For us, this is more about getting there [to the postseason],” Bickerstaff said. “We understand how important these games are and how close and how tight [the standings are]. We feel like we have opportunities to walk some people down that are in front of us. …

“I think it’s too soon to look out and start talking to our guys about, ‘This is the possibility.’”