Ellis scored a season-high 34 points, tied his career high with six steals and played stifling defense against Roy to lead Golden State to a 108-94 victory over the Trail Blazers on Friday night, ending the Warriors' three-game losing streak.
"It definitely gets overlooked," Ellis said. "I hear people say Monta can't play defense, but if you go back and look at the tapes, you don't see Monta getting burned. I can do that day-in and day-out."
The Warriors were playing their first home game since trading disgruntled forward Stephen Jackson to the Charlotte Bobcats earlier in the week. Jackson had been at odds with coach Don Nelson and had been seeking a trade for weeks.
Ellis also had his issues with Nelson and the two got into an argument on the Warriors' most recent road trip. But he came up with his best game of the season, particularly when it came to shutting down Roy, Portland's All-Star guard.
Nelson's plan was to double-team Roy, who went into the game averaging 20.3 points, but Ellis proved he didn't need the extra help while holding Roy to 17 on 6 of 17 shooting, 1 of 5 from 3-point range.
"He had an All-Star performance tonight," said Golden State's Anthony Randolph, who had 15 points and 11 rebounds. "To stop a scorer like that, he really stepped up to the challenge and proved why he's our captain."
The Blazers committed 23 turnovers and shot just 33.3 percent over the final three quarters.
"Everything we talked about doing, we didn't do," Portland coach Nate McMillan said. "The way [the Warriors] play, you can't continue to make those turnovers. They do a lot of things that can get a team frustrated and I think we lost our composure."
The Warriors (4-8) trailed by eight points early but turned the game around when Oden got in foul trouble midway through the first half.
Ellis, who also had eight assists, did the most damage while recording the 17th 30-point game of his career. He had 19 points in the first half, then scored 11 in the fourth quarter when the Warriors led by as many as 20.
Portland, which had held its six previous opponents to 85 points or less in regulation, had no answer. The Blazers (9-5) also struggled McMillan's three-guard offense going despite Golden State playing short-handed.
The injury-riddled Warriors were without injured starters Andris Biedrins (back) and Kelenna Azubuike (patellar tendon) and were forced to sign Chris Hunter from the NBA Development League before the game just to meet the NBA's minimum of eight players.
Hunter started the second half at center and scored four quick points early in the third quarter when Golden State, which led by four at halftime, extended its lead to 64-55. He also helped hold Oden to five points over the final three quarters.
"That guy belongs in the NBA," Nelson said. "Hopefully we find a way to keep him. He's stronger than anybody I have at that position."
Morrow also provided a boost with nine straight points in the third quarter as the Warriors outran and outhustled the Blazers while handing Portland its most lopsided loss of the season.
Oden had 11 points, two assists and a block of Ellis in the first nine minutes of the game but picked up back-to-back fouls in a five-second span in the second quarter and spent the rest of the half on the bench.
Portland, which led 37-29 after the first quarter, struggled offensively without its 7-footer and the Warriors took full advantage.
"We had too many missed opportunities in the second half," Roy said. "We made a lot of turnovers and we were forced into their game. They did a great job of knocking down shots and forcing the tempo."
Morrow and Randolph combined for 12 points, Randolph scoring on a soaring dunk down the lane with 33 seconds remaining, and Golden State closed out the half with a 17-4 run to take a 56-52 halftime lead.
Portland's 37 points in the first quarter were the most by the Blazers in any quarter this season. ... Portland's last win at Golden State came on Nov. 3, 2004.