Beal added seven rebounds, seven assists and five steals and Ariza hit 6-of-6 from 3-point range for Washington, which had not played since finishing off a 4-1 first-round series win over the Chicago Bulls last Tuesday. The Pacers, meanwhile, needed seven games to get past Atlanta, winning Game 7 on Saturday.
Marcin Gortat and Drew Gooden each posted double-doubles in the victory, as Washington won a game in the second round of the playoffs for the first time since 1982. Gortat finished with 12 points and 15 rebounds and Gooden posted 12 points with 13 boards in just under 18 minutes off the bench.
John Wall did his part as well, contributing 13 points and nine assists.
The Pacers, who earned the top seed in the East with a 56-26 regular season mark, won consecutive games to advance past the Hawks but still have not won three straight since a four-game streak against non-playoff teams from March 11-17.
Paul George and George Hill each scored 18 points in defeat.