ATLANTA -- Josh Smith had to wait almost an entire game for his 900th career blocked shot.
He made sure to cash in on the milestone play.
The 23-year-old Smith rejected a shot by Arenas with 4:26 remaining in the game to pass Shaquille O'Neal as the youngest with 900 blocks. O'Neal was 24 years old when he got there.
The block set up a fast break, capped by Smith's left-handed dunk.
"It was special just to block the shot and then be able to finish the play with a perfect assist from Mike Bibby," Smith said.
Smith blocked another shot to cap a strong defensive effort by the Hawks.
"That's impressive, to see somebody block that many shots," said Atlanta's Marvin Williams. "He's got it figured out. He should write a book or something."
Coach Mike Woodson said the Hawks "made a serious effort on defense and rebounding the ball."
Arenas had 23 points and Brendan Haywood added 19 for Washington.
Al Horford had 10 points, 12 rebounds and five blocks for Atlanta.
The Wizards lost forward Caron Butler to a bruised left knee in the second quarter.
"Nothing came up as far as X-rays, but we'll know more tomorrow," said Washington coach Flip Saunders, who added he didn't know if Butler would be available for the team's home opener against New Jersey on Saturday night.
Washington is already without forward Antawn Jamison (right shoulder injury).
A 3-pointer by Arenas capped a 12-0 run for a 12-4 Washington lead. The Wizards led 15-5 before the Hawks closed the opening period with a 15-4 run to lead 29-24.
"It was almost too easy," Saunders said of the Wizards' early lead. "Because what happened is, we were like 'It's going to be an easy one tonight.' And then they put a little bit more pressure on and we turned the ball over, and then they made a quick run.
"They began to gain control of the game in the second quarter when they locked in defensively."
The Hawks led by 15 in the third quarter, the last time at 65-50. Washington cut it to seven points early in the final period as Arenas made three straight baskets.
Atlanta answered with a 3-pointer by Williams before Smith's block and jam pushed the lead to 93-78. The Wizards scored eight straight points before Smith answered with a three-point play.
"The biggest thing was they sustained our punch that we threw in the beginning and we didn't sustain theirs," said Washington's Randy Foye. "We kept fighting but we couldn't get over the hump. They stayed with their stuff and they executed."
Atlanta opened the second period with Crawford and other backups. Crawford had 11 points in the period, including a 3-pointer with 6:26 remaining to push the lead to 10 points for the first time at 43-33.
Bibby forced a turnover by Arenas with 2.7 seconds left in the half to set up a basket by Horford at the buzzer for a 58-44 halftime lead.
The halftime lead matched the Hawks' 17-3 advantage in free throws made in the half. Atlanta made 17 of 19 free throws; Washington made 3 of 6.
"They got to the free throw line," Arenas said. "That's where the game was won."
For the game, Atlanta outscored Washington 31-14 from the free throw line.
Smith's 24th birthday is Dec. 5. ... Team spokesman Brian Sereno confirmed Wizards G Javaris Crittenton had exploratory surgery on his left foot on Oct. 23. Crittenton is expected to miss another month with the strained tendon in the foot. ... The Wizards on Friday exercised their contract options on G Nick Young and C JaVale McGee for the 2010-11 season. ... The Hawks swept last season's series with the Wizards 4-0.