The first round of this season’s NBA playoffs figured to provide a bevy of surprises and exciting action, but few expected that the biggest shocker would come out of the Philadelphia-Detroit series. It is the no. 2 team against the no. 7 team, which is usually a recipe for a four- or five-game snoozer. It’s often so drab that the games are relegated to NBA TV.

Not this time: Despite their 93-84 loss on Sunday night, the Sixers are still poised to pull off a big upset that compares nicely with last spring’s big playoff shocker, the Warriors’ upset of the no. 1-seed Dallas Mavericks in the first round. But if Detroit prevails, another interesting angle emerges: For the first time under coach Flip Saunders, Detroit will have found a way to revive their offense in the postseason after an opponent had taken away their favorite weapon, the three-point shot.

Philadelphia bears some surprising similarities to last year’s Golden State squad. Their regular-season records were the same (40-42), and those marks hid some excellent play after the All-Star break. The Warriors went on a 17-4 tear to qualify for the playoffs on the final day of the season; the Sixers had a 22-9 streak before easing off the gas after clinching their playoff berth with a week to go in the regular season.

Both the Sixers and the Warriors had given their playoff opponents tough times in the regular season. The Warriors swept three games from Dallas; Philadelphia won two of four from Detroit. Both teams are very young and reliant on their athleticism, but it’s there that the similarities end. Whereas the Warriors used their youth and speed to create a potent offense, Philly gets it done with defense. They rotate quickly and clog the passing lanes with their length, and center Samuel Dalembert is an imposing presence in the middle. Philadelphia ranked eighth in the league this season in Defensive Efficiency (points allowed per 100 possessions).

Until the third quarter of Sunday night’s game, it looked like the 76ers would ride that defense to a commanding lead in the series. Their hustling team of guards and forwards were making life miserable for Pistons guard Richard Hamilton, who was shooting 1-12. The team was under 40%, and they had shot 1-6 from behind the arc. Detroit trailed 46-36, and hoops bloggers everywhere must have been starting to speculate on who would be Saunders’s replacement. This would mark the Pistons’ third straight playoff disappointment, and that figured to be grounds for dismissal.

Instead, the Pistons came out in the second half and played 24 minutes of basketball that illustrated why they have been such a fixture in the Eastern Conference Finals (five straight appearances). That sent the hoops bloggers to turn their speculation to the future of Dallas coach Avery Johnson (his team faces the prospect of a third straight disappointment). The turnaround at the Wachovia Center was dramatic, an example of masterful tactics.

In past playoff series, once a team shut down the Pistons’ long-range game, the Pistons would simply writhe and struggle for offense. Sunday night, they tweaked their trademark plays. By rotating the screens for point guard Chauncey Billups to the elbow from the top of the arc, they created an immediate threat that the Pistons guard would drive the lane. This forced Dalembert to stay in the paint to defend the rim and allowed his man, Pistons forward Rasheed Wallace, to drift behind the arc. Before the Sixers could adjust to the new scheme, Wallace, a sharpshooter from deep, had nailed three three-pointers, and the Sixers’ halftime lead disappeared.

With the Sixers scrambling to find their assignments and rotate properly, the Pistons torched them for six three-pointers in the frame. That outside marksmanship opened space for Hamilton to get going. With the Detroit offense back in gear, the Pistons stormed to a 34-16 advantage in the quarter.

Then the story shifted to defense, where the Sixers are the polar opposites of the Pistons. They are one of the worst three-point-shooting teams in the league, so the Pistons altered their defense to pack the middle with everyone except forward Tayshaun Prince, who continued his superb job blanketing his Sixers counterpart, Andre Iguodala. With the middle shut down, the Sixers were bereft of offensive options. Iguodala had averaged 19.9 points per game on 45.6% shooting. This series has been a nightmare for him, as he’s averaged 10.5 points and on a ghastly 22.5%.

Twenty-four minutes away from the brink of a great upset, the Sixers now stand toe-to-toe in a best-of-three slugfest. The upside is that the Sixers have now split eight games with Detroit, so there shouldn’t be the intimidation factor that may have existed at the start of the series. Also, Philly’s solution to Detroit’s defense is rather obvious — run, so that the Pistons don’t get their defense set. Sixers point guard Andre Miller is one of the best in the game at running the fast break, and the team has a roster full of racehorses such as swingmen Thaddeus Young and Rodney Carney, as well as Iguodala and guard Willie Green.

Meanwhile, Detroit will need to keep tweaking their offensive blueprint to create open looks from behind the arc. The Sixers are lightning-quick on rotations when they can anticipate the play. This is a new wrinkle for Saunders, and it bodes well for the Pistons in later rounds — that is, assuming they get by Philadelphia.

mjohnson@nysun.com