Nets star Kyrie Irving has been diagnosed with a left side facial fracture, and is listed as day-to-day. It could potentially lead to the third installment of Masked Kyrie.

Irving sustained the injury on Tuesday during a morning pickup game. He was taken to the hospital and accompanied by coach Kenny Atkinson. Though it’s hardly the way he had hoped to start his Nets tenure, it’s certainly not worst-case by any means.

The Nets handed Irving a four-year, $141 million max deal on June 30, the first day of free agency. And though the New Jersey-bred point guard has a history of facial injuries, that history would also imply this one isn’t likely to cost him any playing time.

The Nets don’t open the preseason until Oct. 4 against Sesi/Franca Basketball Club of Brazil, and will face LeBron James and the Lakers six days later in Shanghai. The regular-season opener isn’t until Oct. 18 at Barclays Center against the defending NBA champion Raptors.

This is the third time Irving has suffered a facial injury and could well require a mask.

Irving, while with the Cavaliers, suffered a broken jaw against the Bucks on Dec. 14, 2012, playing in his third game back after a three-week absence for an index finger injury. He flew to New York to get fitted for a protective mask and played the next day against the Knicks, going off for a then-career high 41 points at the Garden.

After being traded to the Celtics, Irving left a game against the Hornets on Nov. 10, 2017 with a minor facial fracture, and bleeding to the nose after being elbowed by Celtics teammate Aron Baynes. He missed the next game, then returned to face the Nets on Nov. 14.

The Nets are on the verge of rounding out their roster, and it won’t include ex-Knick Carmelo Anthony — but it may include his former teammate Lance Thomas.

The Nets signed 6-foot-11, 265-pound center John Egbunu and swingman C.J. Williams. On Tuesday, The Post was the first to report the Nets had brought Egbunu to camp, and also cited interest in the Brooklyn-born Thomas. Now The Athletic writes they’re “progressing” toward a deal with the 31-year-old Thomas.

Egbunu, 24, is imposing and showed great athleticism at Florida before a torn ACL cut short his junior season and robbed him of his senior campaign. He averaged 10 points and 6.5 rebounds in 24.0 minutes over 58 games in his sophomore and junior years.

Williams spent the past two seasons as a two-way player for the Clippers and Timberwolves, averaging 4.7 points in 15.7 minutes over 53 games. The 6-5, 226-pound guard signed a non-guaranteed contract.

Egbunu getting a camp spot leaves the Nets with 19 players, and room for one more. That appears to be earmarked for Thomas.

Thomas — who attended high school at both Scotch Plains-Fanwood and St. Benedict’s Prep in New Jersey — was the longest-tenured Knick before they waived him the night before free agency to clear cap space in pursuit of Irving and Kevin Durant. He’s a stout defender, solid locker room presence and decent shooter, shooting 38.3 percent from deep.

The Nets have 15 guaranteed deals, as well as Exhibit 10s Deng Adel and Egbunu, as well as ex-Knick Henry Ellenson on a two-way. They added Williams, who is eligible for a two-way despite being 29. Thomas would take the final spot.

The Nets can add an extra regular player after the fifth game of Wilson Chandler’s 25-game PED suspension, and general manager Sean Marks confirmed Tuesday they’ll look into doing that.

“Yeah, we would definitely look at that. Like always, you keep all your options open as long as you can,” Marks said. “That’s what we’ll do.”