If Isaiah Whitehead is going to get schooled, he figures he might as well ask a few questions.

With Nets starter Jeremy Lin out with a sore hamstring, Whitehead has been matched up against some of the best point guards in the game. This time it was Damian Lillard, who helped lead the Trail Blazers to a 129-109 win over the Nets on Sunday at Barclays Center.

Whitehead, a rookie from Seton Hall, said he has long been a fan of Lillard, and decided he might as well use the game to pick his brain.

“While we were shooting free throws or they were shooting free throws, I was asking him questions,” Whitehead said. “He’s either going to answer them or he’s not. He was great enough to answer them. I asked him how he got so quick and how do you read ball screens. I’m trying to learn as much as possible. I just went for it.”

Give Whitehead, who shot 2-for-10 and had 11 points and two assists in 24 minutes, credit for trying to make something positive happen while the Nets wait for Lin to return. They are 2-6 without Lin after going 2-3 with him to start the season, and they have lost four straight as they fill in with a lineup of inexperienced point guards.

Although Lillard’s 18 points were far below his 28.7 average, he efficiently ran an offense that shot 57.6 percent, including 41.7 percent from three-point range.

advertisement | advertise on newsday

“I thought before this game we were doing a decent job defending the three-point shot, but that wasn’t the case tonight,” Nets coach Kenny Atkinson said. “We’re plugging holes right now defensively in different places, so we’re going to have to regroup. Get some practice time, get some film time, get our principles back.”

Guard C.J. McCollum had 33 points and was 6-for-10 from three-point range for Portland (8-7), which ended a three-game losing streak. Brook Lopez led the Nets with 21 points and shot 8-for-14, including 2-for-4 from three-point range. The 7-foot center’s 22 three-pointers put him second on the team behind 7-footer Justin Hamilton, who made three and has 23.

The Nets kept the game competitive for a half, but McCollum’s long-range shooting helped the Blazers break it open with a 27-14 run to open the second half. McCollum was 4-for-4 on three-pointers in the third quarter.

The third quarter has been the Nets’ Achilles’ heel all season, and they haven’t figured out a way to fix the problem. “I just think we come out flat,” Lopez said. “I think it’s on us 100 percent.”

One solution might be to get Lin back on the floor, but no one seems to want to make a projection about when that might happen. The Nets seem happy with what they heard after he was examined Thursday, but there are no definitive public projections for his return.

“Jeremy is progressing well,” Atkinson said before the game. “I can’t give you a timetable or update. He’s progressing on schedule.’’

When Lin strained his hamstring Nov. 2, the team estimated he would be out for two weeks. Eighteen days later, they played their eighth game without him.

So Nets fans sit and wait. In the meantime, Whitehead will continue to ask questions. Next point guard up? The Celtics’ Isaiah Thomas on Wednesday.