The Nets’ biggest need is at point guard. They’ve admitted as much. But are there any lead guards available who could make a difference on this 21-61 team? And will new general manager Sean Marks be able to land them?

With more than $40 million in cap space but no first-round pick, Marks will have to rely on free agency and ingenuity to fix the problem.

The Nets have three point guards on their roster. Starter Jarrett Jack is likely to be bought out at $500,000 after tearing his ACL, and backup Shane Larkin having until June 29 to decide whether he will exercise his $1.5 million player option.

NBA sources said the only free-agent point guard who would be a difference-maker is Mike Conley. He led the NBA in assist-to-turnover ratio and will be the top priority for several teams, including the Knicks and his own Grizzlies. Memphis can offer Conley more than $100 million, and GM Chris Wallace guaranteed they would re-sign him.

But Conley’s odds of bolting Memphis could be increased by the Saturday firing of Grizzlies coach Dave Joerger and reports of Wallace’s potential departure.

“We need to be committed to doing the things, whatever it may be and however hard the decision may be, to do the right things,’’ Conley said after the season, of which he missed the final month due to an Achilles tendon problem.

So what do the Nets do in the likelihood they don’t land him?

New coach Kenny Atkinson has a reputation as a point-guard whisperer, and Jeremy Lin repeatedly has credited him for his help during Linsanity when Atkinson was a Knicks assistant.

Lin piqued the Nets’ interest before signing with the Hornets last July, and is a viable candidate if he opts out of his $2.2 million deal. But he told the Charlotte Observer he wants to re-sign with the Hornets.

“I would love to,’’ said Lin. “I don’t like moving every year. I don’t like packing and unpacking boxes.’’

The rest of the free agents available are either journeymen or carry huge question marks.

The Celtics and Mavericks gave up on Rajon Rondo for a reason, and the drama (remember his anti-gay tirade at referee Bill Kennedy?) may be too much to stomach.

Brandon Jennings, in whom the Nets showed interest in February, missed 11 months with a torn Achilles tendon suffered in January 2015. He was shipped to Orlando at this past season’s trade deadline and underwhelmed.

Ty Lawson’s declining play, shady attitude and off-court problems (a domestic violence and four DUI arrests, including two last year) led him to get traded by Denver and bought out by Houston in March.

Brooklyn could be creative and either go international or overpay for a young player on the rise, such as restricted free agents Seth Curry or Jordan Clarkson.

With the Lakers having Julius Randle and D’Angelo Russell, the Nets could test their resolve by overpaying Clarkson. Seth Curry, brother of Steph and son of Dell, declined his player option with the Kings, who turned him loose over the last 11 games and saw him average 15.2 points. Would the Nets bank on his bloodlines?

The Nets are almost sure to be active in the international market — with Marks, Atkinson and assistant GM Trajan Langdon having played a combined two decades in Europe, and Mikhail Prokhorov having owned CSKA Moscow.

Langdon, who played for CSKA Moscow, reportedly was scouting in Europe last month and may have checked on his old club, which is in the Euroleague’s final four next weekend behind a pair of intriguing 6-foot-5 guards.

Serb Milos Teodosic, 28, is a deft passer and Europe’s top point guard. He has a year left on a $2.5 million deal, which doesn’t have an NBA out. Scoring combo-guard Nando de Colo, who played 97 games for the Spurs while Marks and Langdon were in San Antonio’s front office, is a free agent.

On Friday, CSKA Moscow plays Lokomotiv Kuban, led by All-Euroleague first-teamer Malcolm Delaney, who wants to play in the NBA. Ex-Knick Sergio Rodriguez, who makes $2.6 million at Real Madrid, bears watching as well.