Stifling defense helped the UO women's basketball team beat Arizona on Friday night, 62-44, to secure the Ducks' first ever 5-0 start to conference play and give them sole possession of first place in the Pac-12.Oregon (16-2) shot a season-low .382 but held Arizona to .293 shooting — including a 2-of-18 stretch to open the second half. "We couldn't possibly shoot worse," said UO coach, who in a pregame ceremony received a commemorative ball to celebrate his 500th career coaching win earlier this season. "I don't think we took a bad three all night; those are shots we typically make. I don't know what the deal was, but we've got to do a better job. … Thank goodness we did defend pretty well tonight, for the most part.": Arizona's rough shooting night wasn't apparent from the start, as the Wildcats (4-12, 0-5 Pac-12) made 4-of-7 attempts to open the game and take a 10-3 lead. Oregon's sophomore superstars,and, helped restore order, scoring every UO point as the Ducks closed out the quarter on a 16-4 run for a 19-14 lead.The Ducks' shooting woes became apparent in the second quarter, when they went just 2-of-13. Both field goals were three-pointers by, part of an 8-0 run midway through the quarter that amounted to all of Oregon's offense in the period. The UO women finally gained some separation by clamping down on defense in the third quarter, holding Arizona without a field goal until there were just 40.7 seconds left in the period; that basket was sandwiched between a pair ofthree-pointers, and the Ducks took a 45-31 lead into the fourth.: Ionescu finished with a game-high 22 points, the last a three-pointer for Oregon's biggest lead at 54-34 in the fourth quarter. She also grabbed 11 rebounds and dished out four assists. Cazorla added nine points with six assists, and Hebard added 14 points with six rebounds.typified the UO shooting frustrations; she opened the game with a three-pointer and made two straight for Oregon's final points of the night, but in between missed eight in a row, a couple of them rolling around the rim and falling out.Oregon entered the night having matched the best start to conference play in school history at 4-0, and extended it with the win. The Ducks had been tied with their opponent Sunday, Arizona State, for first place in the Pac-12, and now are alone on top after the Sun Devils lost Friday at Oregon State.The Ducks host No. 18 Arizona State in Matthew Knight Arena on Sunday (5 p.m., Pac-12 Network).