The Sixers are heading back to Madison Square Garden, and they do so knowing if they do not bring their best, it will be the final 48 minutes of basketball they play in the 2023-24 NBA season.

The Sixers fell to the New York Knicks in Game 4 of the first round of the Eastern Conference Playoffs, and they did so because when the chips were down, they were not the ones who rose to the occasion. All-Star point guard Jalen Brunson erupted, dominating the Sixers to the tune of 47 points and 10 assists, and the Knicks' impressive collection of role players followed his lead. Meanwhile, reigning NBA MVP Joel Embiid missed all five of his field goal attempts in the fourth quarter -- a period in which the Sixers managed just 16 points.

In a macro sense, the task at hand for the Sixers is to defeat the Knicks in three straight games -- with the first and last being played at the world's most famous arena. But for Tuesday, just winning Game 5 and living to see another day will do.

Here is what I will be watching for as the Sixers try to avoid elimination and bring the series back to Philadelphia:

How the Knicks defend Embiid

Embiid was not his best self, but okay as a scorer, for the first three quarters or so of Game 4. With Knicks backup center Mitchell Robinson unavailable during the game after aggravating his ankle injury in the second quarter of Game 3, Embiid drew the fifth personal foul on New York's starting five, Isaiah Hartenstein, with 1:25 remaining in the third quarter. The Sixers led by two, Knicks head coach Tom Thibodeau was forced to replace Hartenstein with third-string center Precious Achiuwa, and suddenly it appeared as if Embiid and the Sixers had a chance to blow the game open.

The exact opposite happened.

Not only did Achiuwa change the game with his athleticism and energy: he might have swung it from a Sixers win that would have evened the series at 2-2 into a massive road victory for the Knicks. Achiuwa played the remaining 13 minutes 

But it stemmed from Thibodeau using him in an unconventional manner, and another first-year Knicks player stepping up.

Achiuwa, rather than defending Embiid, was used as a roamer of sorts, interrupting plays as a help defender and tapping into his special athletic tools. Defending Embiid was OG Anunoby -- yes, the same player who spent the first three and a half games of the series defending Sixers All-Star guard and the NBA's Most Improved Player, Tyrese Maxey.

Because of a combination of Anunoby's special defensive versatility, the disruptions caused by Achiuwa, poor execution and organization from all parties involved with the Sixers and fatigue from Embiid -- who played the entire second half, the first time he has ever played an entire half in his NBA career (regular season or playoffs) -- it worked. 

The Knicks outscored the Sixers by seven points over the final 13:25 of play, and it is thanks in large part to their tremendous defense against Embiid. With Robinson's status for Game 5 up in the air, Embiid could very well see a whole lot more of Anunoby's impressive fronting and Achiuwa's damaging help defense. Even if Robinson does play, Thibodeau could go back to that look in spurts moving forward.

How Nick Nurse responds with his back against the wall

Nurse, the Sixers' first-year head coach, has long been known for his outside-the-box thinking and willing to be unconventional. Oftentimes, being radical is not necessarily a good thing when you are in charge of a team -- having a cool hand and being consistent can go a long way over the course of a season.

Sometimes, though, significant changes are necessary in order to survive. Nurse may find himself in one of those situations.

In the Sixers' Play-In Tournament victory over the Miami Heat, Nurse finally decided he would not close with Tobias Harris on the floor, and it paid dividends: Nic Batum gave the Sixers the game of his life and saved their season. In Game 3 against the Knicks, Batum once again closed over Harris.

Those two games have one other thing in common aside from Batum's presence over that of Harris at the end of the game: the Sixers actually won.

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There are serious potential drawbacks to inserting Batum into the closing lineup, particularly with Kyle Lowry now firmly entrenched in that unit: both veterans have bolstered the Sixers' rotation with timely three-point shooting, crisp passing and versatile defense, but they also each offer little to no shot creation at this junctures of their careers. So, removing the struggling Harris from the most important minutes of the game is not necessarily as easy as it sounds. But at the same time, Batum is a considerably better defensive player than Harris who is also much more reliable to make proper decisions on both ends of the floor.

Nurse has coached with extreme urgency in every postseason game the Sixers have played. But if Game 5 goes down to the wire like the four contests preceding it, which players Nurse ultimately puts his faith in will be quite telling.

How the Knicks fight back against the injury bug

Robinson missed the second half of Game 3 and the entirety of Game 4, and the Knicks responded by inserting Achiuwa into their rotation and watching him thrive. But even if Robinson returns in Game 5 -- he is listed as questionable with a left ankle sprain as of this writing -- the Knicks' rotation is not going to look exactly like it did for the first few games of this series.

Bojan Bogdanovic, who knocked down three triples in each of their first two games of this series for the Knicks, went down with a left foot contusion after 71 seconds of action in the second quarter of Game 4 and did not return to action. Bogdanovic -- who reportedly could already need wrist surgery after the playoffs conclude -- has already been ruled out for Game 5. How Thibodeau adjusts his rotation will be fascinating.

Brunson (who is listed as probable after "tweaking" his knee in Game 4, but is expected to play), Donte DiVincenzo, Josh Hart, Anunoby, Isaiah Hartenstein and Miles McBride will be in New York's rotation no matter what. But that list is only six players long. Most coaches go with eight players in the playoffs, which is what Thibodeau has done so far.

If Robinson plays, he gives the Knicks a seventh piece. If that is the case, even with Hartenstein and Robinson in the mix, Achiuwa has likely earned more playing time. It may sound odd, as Achiuwa is New York's third-string center, but he has also played significant minutes at power forward for the Knicks this season, particularly during the extensive period in which Anunoby missed time due to an injury.

If Robinson plays and Achiuwa is used as a roaming power forward rather than a center -- where, as we saw in the second half of Game 4, he can thrive -- the Knicks will have an eight-man rotation. It will be unconventional, but it will be eight viable NBA players.

If Robinson does not play, though, Thibodeau will either have to trim his rotation even thinner to seven guys -- which even for a head coach who notoriously trusts very few bench players, may be a bit extreme this early in the playoffs -- or dig deeper into his bag to replace Bogdanovic with someone who possesses more perimeter skills.

New York's head coach's top two options if that becomes the case are two players who used to play for the Sixers: the favorite is Alec Burks, who the Knicks acquired at the trade deadline alongside Bogdanovic from the Detroit Pistons but quickly played his way out of the rotation. This is Burks' second stint with the Thibodeau-led Knicks, and the experience there likely gives him the edge over our old friend: Shake Milton.

Milton signed a two-year pact with the Minnesota Timberwolves last summer after spending the first five seasons of his career in Philadelphia, but had a disastrous start to the season that led to his exile from the rotation. Milton was eventually used as salary filler in a trade with Detroit, where he played four games -- under a former Sixers assistant coach, Pistons head coach Monty Williams -- before Milton and the Pistons agreed to a buyout, which cleared the way for him to sign with New York and fill out the end of their bench.

Robinson's status is not just important because of the value of his play: now that Bogdanovic is out, whether or not Robinson is at Thibodeau's disposal will determine whether the Knicks consistently deploy heavy lineups featuring lots of size, or go to ones that feature more perimeter-oriented players.

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