Among concerns over the ailing left knee of their two-time all-star center, their point guard riling up the fan base, their backup center in a cell phone fiasco, the 76ers have a bigger problem at hand – dealing with the Brooklyn Nets.

The Sixers are down, 1-0, in their best-of-seven opening-round Eastern Conference series after Saturday’s uninspiring 111-102 loss.

In their history, the Sixers have never lost the first two games of a playoff series and then come back to win it. So, Monday’s 8 p.m. Game 2 at the Wells Fargo Center is more-than-fairly important for a team that has aspirations of a deep postseason run.

Joel Embiid, who had 22 points and 15 rebounds after being listed as doubtful to play due to left knee soreness, is listed as questionable on the NBA injury report, which came out late Sunday afternoon.

Embiid didn’t practice on Sunday, but coach Brett Brown said the high-minute players did more video work, while the low-minute guys did most of the physical activity. Brown was cautiously optimistic when asked about how Embiid came out physically after Game 1.

“I think he came out OK, but we are going to learn more as he is going through a lot more layers of treatment,” Brown said

Meanwhile, 24 hours after receiving backlash for his comment about the fans, point guard Ben Simmons sent out an olive branch.

After Saturday’s loss, when asked about the booing fans, he said, “If you’re going to boo, then stay on that side. That’s how I feel, if you’re a Sixers fan and you’re going to boo, then stay on that side.”

The Philadelphia fans didn’t take kindly to those remarks.

When asked for his reaction to the fans’ reaction, Simmons went into positive mode.

“I love it, that is how Philly is,” Simmons said. “If you can’t play, they will give you the [bleep] and talk [bleep], it is what it is.”

He was just getting warmed up.

“[If] you are not playing well they will let you know, but I love being here I love the fans here. I wouldn’t want to be in a place where they didn’t really care or only showed up when times were going well. A few years ago they were winning 10 games.”

Of course, what the fans should be talking about is Simmons not playing up to his all-star status, scoring nine points, with as many turnovers (3) as assists. He shot 1 for 5 from the foul line and was a minus-21.

“I didn’t feel I was aggressive enough,” Simmons said. “I feel I could be more aggressive. I had [Jared] Dudley and the other kid guarding me and had to be aggressive.”

The “other kid” was Treveon Graham.

According to ESPN Stats & Info, Simmons shot 1 for 5 against Dudley, 1-1 against Graham, 1-2 against D’Angelo Russell, and 1-1 against DeMarre Carroll.

No new ground was covered on the Amir Johnson situation, when he was caught on camera in the fourth quarter looking at a cell phone with Embiid.

“I hate that it ever happened. I put a statement out there and said what I said, that is pretty much the situation,” Johnson said after practice.

Embiid had said on Saturday that Johnson had a phone because his daughter “was extremely sick.”

When asked if his daughter was OK, Johnson said, “Yep.”

Brown said that Johnson addressed the team before practice about the situation.

The No. 1 concern for the Sixers coach is getting back in this series against a Nets team that seemed to have an open highway to the basket. Improving their three-point shooting is a must after going 3-for-25.

There are so many concerns that have occurred after just one game as the Sixers look to turn around the series, and their season as well.