Houston won 25 of their first 29 games to notch the NBA's best record but have since entered their worst tailspin in nearly five years.
Otto Porter Jr scored 26 points and Bradley Beal and Kelly Oubre Jr 21 each as Washington beat the Rockets 121-103 on Friday night for their fifth straight loss.
It's the longest skid for Houston since dropping seven straight from January 9-19, 2013.
NBA scoring leader James Harden matched his season low with 20 points for the Rockets.
Chris Paul returned after missing three games with a strained groin and had eight points and six assists in 26 minutes.
Houston had completed a 14-game winning streak before the alarming slide.
"We just haven't had a rhythm in these last five games, quite frankly," Harden said.
"We had pretty good spurts but just a consistent four-quarter game, we haven't had that. So hopefully we get back home and kind of buckle down a little bit."
A night after blowing a 26-point lead in Boston, the Rockets held their last lead midway through the first quarter en route to their worst defeat of the season.
Houston has by far the most 3-pointers in the league this season but was held to 29.2 per cent (14 for 48) from deep.
Though Paul was back, the Rockets were missing center Clint Capela with an orbital fracture for the second straight game.
"Mentally we're fine," Rockets coach Mike D'Antoni said.
"We've got some tired legs and missing the big guy in the middle to give us a force to the rim. ... We've got all kinds of excuses but that doesn't work, it doesn't matter. We lost, they won. They're the better team tonight."
