PHILADELPHIA — Leading up to Game 1 of the first-round playoff matchup between the Washington Wizards and Philadelphia 76ers, much of the basketball world’s attention was focused squarely under the basket. The low post contained much of the intrigue in this series, considering one team has MVP finalist Joel Embiid and the other has a quirky trio of centers working in rotation.

But much to the delight of the 11,160 fans who streamed into 50 percent-capacity Wells Fargo Center, Sunday afternoon’s bout was decided not in the paint but at the game’s margins — in a slight turnover disparity, just a couple of three-pointers and, most significantly, lopsided free throw numbers.

Philadelphia converted its mastery of the game’s minutiae into a 125-118 win and an early 1-0 edge in the best-of-seven series. Game 2 is scheduled for Wednesday night.

“We made some costly mistakes, and this team is a veteran, loaded team,” Wizards Coach Scott Brooks said. “They capitalized. They don’t wait for the next time you make that mistake. … They don’t have to sniff one out. They know it, and they just capitalize on it.”

The most dramatic flub came with 37 seconds left, when Washington trailed by just five after 76ers guard Ben Simmons missed a pair of free throws. Wizards center Daniel Gafford collected the rebound and got the ball to Russell Westbrook, but Westbrook’s heel just caught the sideline, and the ball went back to Philadelphia.

Brooks challenged the call to no avail. From there, the 76ers iced the game at the free throw line.

“Yeah, I mean, it is what it is,” a taciturn Westbrook said when asked about the play. “I mean, it don’t matter now. It doesn’t matter.”

Westbrook’s frustration felt fitting for a game in which the Wizards handled the big things correctly but struggled to elevate a level for the playoffs, in which focus cannot waver for a single possession — especially against a team as thorough as top-seeded Philadelphia.

Washington did well handling the 76ers’ length, outrebounding them by a single board. It also shared the ball well, supporting Bradley Beal and his team-high 33 points by shooting 55.7 percent from the field. It even hit eight threes, a high count for the Wizards.

But the team doomed itself with over-fouling. It sent Philadelphia to the free throw line a hefty 33 times, and though the 76ers helped by making just 23, all the fouls took the Wizards out of rhythm and afforded the 76ers just enough breathing room to feel comfortable.

Embiid worked his way to a 30-point performance after a slow start thanks in part to a game-high 12 made free throws on 13 attempts. The Wizards finished 12 for 15 from the line as a team.

“They’ve got good players,” Brooks said. “A big portion of our guys are playing in the playoffs for the first time. ... I thought [starting forward Rui Hachimura] was pretty solid. I thought [starting center Alex Len] was pretty solid — they just played better than us. We put them on the free throw line. That’s a big discrepancy. I’m not complaining about it; we fouled. They’re good players. They put you in tough situations. I think we could’ve gotten there more, but we did foul them.”

Washington emerged from the locker room at halftime with a 62-61 lead, but Tobias Harris, Danny Green and Seth Curry got hot from three-point range to spark a run that gave Philadelphia a seven-point advantage. Another three-pointer from Harris put the 76ers up 11 early in the fourth quarter, putting the Wizards on their heels.

Washington’s eight threes helped keep the Wizards competitive, but four came from Davis Bertans (14 points), two came from Hachimura (12 points, five rebounds), and one each came from Beal and Raul Neto. The 76ers had a greater diversity of perimeter threats — Green went 3 for 4 and Curry 3 for 9 from distance — and challenged the defense by attempting 32 shots from distance.

Harris did the heavy lifting for the 76ers, scoring 37 points, including 28 in the first half.

“In the third quarter I thought we gave them opportunities to get out in transition and easy buckets on some of our transition mess-ups and switch mess-ups, but we can play better,” Brooks said, “and that’s the good thing.”

Westbrook finished with 16 points, 14 assists and five rebounds. Gafford and Len had 12 points apiece. In addition to his 33 points, Beal added a playoff-career-high 10 rebounds and six assists.

He said his positive takeaway from Game 1 is that the Wizards haven’t hit their ceiling.

“We didn’t play great at all, and we were still in the game, still had an opportunity to win,” Beal said. “That’s what kind of keeps me going, keeps me motivated: the fact that — I don’t think I played great. I don’t think I had a good game. I think we’ve still got a couple levels we could tap into from everybody across the board. I think that’s the team we were, how we finished off [the regular season]. We didn’t necessarily have that same intensity tonight. We have to get back to that and understand that these games are an A-plus-plus level. We’ve got to bring it every night.”