Otto Porter Jr. scored 21 points, including 15 in the third quarter. Here, he puts in on the floor against Cleveland’s Richard Jefferson. (Patrick Smith/Getty Images)

When the Washington Wizards received word early Sunday afternoon that the Cleveland Cavaliers would not have LeBron James at their disposal for the teams’ matinee matchup, the conversation in the home team’s locker room at Verizon Center did not change much.

Even without the four-time MVP, the Cavaliers remained potent, and the Wizards had squandered opportunities against the depleted Miami Heat and Chicago Bulls, two other teams ahead of them in the Eastern Conference standings, over the previous seven days. Washington still needed to play with urgency because it still needs victories against anyone and everyone, whole or incomplete, during this playoff push.

The Wizards couldn’t afford another letdown and didn’t have one, capitalizing on James’s respite with a breezy 113-99 victory as James, to the chagrin of the capacity crowd, watched from the end of the Cavaliers’ bench to give his body a day off in the midst of three games in four days.

The Wizards improved to 28-30 and 5-2 since the all-star break with the win, their fifth straight at home and second straight overall. The first-place Cavaliers dropped to 41-17 and 3-12, including 1-9 on the road, without James since he returned to Cleveland last season.

“That’s a definitely a good sign for us, a good step for us,” said Wizards guard Bradley Beal, who scored 17 points in 25 minutes off the bench. “We need to come out with the mentality that no matter who’s playing, we’re going to come out and play hard, and we did that.”

Timofey Mozgov, right, fouls Washington’s Ramon Sessions from behind. (Toni L. Sandys/The Washington Post)

Cavaliers point guard Kyrie Irving topped all players with 28 points, but his counterpart was Washington’s catalyst. While Irving is a scoring dynamo, John Wall exhibited his all-around repertoire with a dose of veracity that has been fleeting from him this season. The three-time all-star point guard was in attack mode from the tip, routinely shattering Cleveland’s shabby transition defense.

Wall finished with 21 points, 13 assists and seven rebounds in 30 minutes, falling three boards short of his third triple-double of the month without stepping on the floor in the fourth quarter. Most importantly, he spearheaded the Wizards’ defense, which held the Cavaliers to 40 percent shooting.

“It starts with John, no question,” Wizards Coach Randy Wittman said. “He’s at a position in this league where he doesn’t get many nights off. . . . He’s been locked in here more recently. It starts with him. That trickles down.”

The game was decided in the third quarter when the Wizards, regularly victims of third-quarter collapses, emerged from halftime to swiftly expand their nine-point lead behind a parade of three-pointers from Otto Porter Jr. The third-year forward, who had his aggression questioned again last week by Wittman, drained a trio of three-pointers in the first 1 minute 56 seconds of the period for a personal 9-0 spurt and scored 15 points in the quarter — one less than the Cavaliers. He finished with 21 points, his highest total since Feb. 6.

On Feb. 20, the Wizards faced a Heat team without Chris Bosh and Dwyane Wade. On Wednesday, they encountered a Bulls squad without Derrick Rose, Jimmy Butler, Nikola Mirotic and Joakim Noah. Washington lost both.

John Wall nearly had his third triple-double of the month, finishing with with 21 points, 13 assists, and seven rebounds in 30 minutes. ( / )

James’s absence was another break. He leads Cleveland in points, assists and minutes per game and is third in rebounds. But the Cavaliers still feature Irving and Kevin Love — two of the sport’s top offensive talents — and they turned to the pair immediately and often.

First, Cleveland attempted to capitalize with the smaller Jared Dudley defending Love. Three of the Cavaliers’ first four possessions ended with Love taking a shot from the post. Then the baton was transferred to Irving.

The score-first point guard torched the Wizards with 19 points in the fourth quarter in the teams’ previous meeting — a 121-115 Cavaliers victory Jan. 6 — by feasting on isolation plays. In that matchup, Washington switched on every ball screen defensively, and Irving easily found himself opposite overwhelmed, lead-footed big men on the perimeter. It was the first time the Wizards had utilized the strategy all season, and it was a debacle.

They made an adjustment Sunday: No switching big men along the perimeter. Irving still generated his points and produced 10 in the first quarter, but Love was held to 12 points — six of which came in the game’s first 3:16 — and five rebounds as the Wizards have held opponents to fewer than 100 points in five of their seven games since the all-star break. They have won all five.

“I think we just came out focused,” Wall said. “We were going to come out with a lot of intensity whether LeBron played or not. It’s just a big game for us.”

Up next for the Wizards are the Philadelphia 76ers and Minnesota Timberwolves, two of the NBA’s worst teams, before they meet the Cavaliers again Friday with an opportunity to claim the four-game season series. James figures to be on the court for that game.

“Right now we really don’t care who plays,” Wizards swingman Alan Anderson said. “LeBron playing or not, we need some wins.”