Washington, not known for its defense, limited Philadelphia to just nine points in the pivotal 12-minute period, which started with Philadelphia holding an 84-78 lead.
Antawn Jamison led Washington with 25 points and 13 rebounds. Arenas scored 20 with seven rebounds and five assists.
DeShawn Stevenson had 19 points and seven assists. Antonio Daniels scored 12 with six assists, while Darius Songaila added 10 points, four rebounds and four assists for the Wizards, who have won four of five.
The loss hurt Philadelphia's chances to grab the seventh playoff seed in the Eastern Conference.
2014: The Year in Music [PHOTOS]