Hard to say which was worse Friday: the Nets’ ballhandling or their defense. 

What’s clear is they fell back into their losing ways, suffering a 121-102 thrashing at the hands of the Trail Blazers before a sellout crowd of 18,018 at Barclays Center. 

The loss marked their third straight, after a hot stretch that had seen them win seven of nine. 

The Nets’ lack of point guard play — with D’Angelo Russell hurt and Ben Simmons bought out — again forced them to start 10-day signee Killian Hayes.

It showed on the court, with the Nets tying a season-high by committing 22 turnovers. 

That saw Portland get into early offense, as the Nets allowed a staggering .577 shooting from the field, their second-worst defensive performance of the season. 

The Nets (21-38) are two games behind the Bulls — pending the result of Friday night’s game against the Raptors — for the final play-in spot in the Eastern Conference.

They were seventh in the lottery odds, a half-game below No. 6 Philadelphia and three below No. 5 Toronto. 

The Nets led only briefly before conceding a 13-5 run to fall behind 16-11 less than midway through the first quarter. 

Then Portland’s high-flying Shaedon Sharpe (game-high 25 points, five assists) hit a 3-pointer to cap a 15-6 blitz that left the Nets down 44-31 with 7:09 left in the half. 

The Nets never got closer than nine the rest of the night and trailed by as much as 26 in the fourth quarter. 

Hayes, Nic Claxton and Cam Thomas, who played for the first time since Jan. 2, all shared team-high honors with 16 points.