The Celtics take a 2-0 lead with a stunning 108-103 victory at the TD Garden Thursday night.

Jim Fenton The Enterprise @JFenton_ent

BOSTON – They began developing into a resilient team last October, a trait that is still obvious nearly seven months later.

Though up an obstacle in front of the 2017-18 Celtics, and they’ll find a way to overcome it, whether it be injuries to key players or large deficits against quality teams.

That has been the story of the season starting with the opening-night gruesome injury suffered by Gordon Hayward, and remarkably, the resiliency is alive and well in the second round of the playoffs.

For their latest trick, the Celtics spotted the Philadelphia 76ers a 22-point first-half lead in Game 2 of the Eastern Conference semifinal round, looking like they didn’t belong on the same court.

Overmatched? Not quite as it was just another obstacle for these amazing Celtics to hurdle over.

A stirring comeback that began late in the second quarter and carried over into the second half resulted in a remarkable 108-103 victory over the stunned 76ers Thursday night at the rockin’ TD Garden.

With All-Stars Hayward and Kyrie Irving not available, the Celtics own a 2-0 series lead and are two wins away from a return trip to the Eastern Conference finals.

“I would say that was a win that was largely attributed to unbelievable effort of our players,’’ said coach Brad Stevens, “and the other 18,000 people in here because that was one of those deals we needed everybody engaged in the game. It was a special environment.’’

Indeed it was as the Celtics turned a 48-26 deficit near the midway point of the second quarter into a 74-66 lead with 3:05 left in the third quarter, putting together a 50-20 run over the span of just over 15 minutes.

The Sixers recovered to take the lead again, but the Celtics responded down the stretch to grab their sixth straight postseason home win and head to Philadelphia Saturday with momentum.

It was the Celtics’ largest comeback in the playoffs since rallying from 24 points down to win Game 4 of the NBA Finals against the Los Angeles Lakers in 2008.

Once again, there were plenty of contributors with rookie Jayson Tatum getting 21 points, Terry Rozier (6 for 15) overcoming a rough shooting night to score 20 points with nine assists and seven rebounds, and Marcus Smart scored 19 points with four 3-pointers.

Al Horford did a little bit of everything once again with 13 points, 12 rebounds and five assists, Jaylen Brown returned from a strained hamstring to score 13 points and Marcus Morris chipped in with 11 points.

The Celtics were brutal at both ends in the opening 20 minutes of the game, then ended the half with an 18-3 run that got the crowd into it and cut the 76ers’ lead to 56-51 at the break.

“I thought we were too sped up on offense and we were doing our own thing and we weren’t playing with any togetherness on defense,’’ said Stevens. “We just said we need to do our jobs first and foremost and hopefully if you do that enough of the time we’ll have a chance to get back in this thing.’’

Said Rozier: “They definitely punched us in the mouth and we had to bounce back.’’

The Celtics found themselves behind again, 93-88, with less than six minutes to go, but they went on a 20-10 run to close the game and take command of the series. Rozier hit a pair of 3-pointers in the spree with Morris adding another after grabbing an offensive rebound.

The Sixers were led by JJ Redick with 23 points, including five 3-pointers, Robert Covington (22) and Joel Embiid (20 points, 14 rebounds), but the likely rookie of the year, Ben Simmons, was bottled up, getting one point in 31 minutes.

According to Elias, the last time a rookie of the year went without a field goal in the postseason game was Jerry Lucas in 1964.

“I think, mentally, I was thinking too much, overthinking the plays,’’ said Simmons. “Wasn’t just out there, flowing, playing the way that I play, which is free.’’

The Celtics now head to Philadelphia to face a team that had won 20-of-21 games before this series started but is now in a 2-0 hole.

 “You move on,’’ said Sixers coach Brett Brown. “Nobody’s crying. We’re not begging for anything. We’re going to walk out of Boston knowing they did what they had to do. They won two games at home and we’re going to have to reciprocate.

 “There’s not going to be a pity party. We give them credit and we look forward to coming back and playing in Philadelphia.’’