National Basketball Association roundup

A 10-time All-Star, Pierce spent the first 15 years of his career with the Celtics, helping the club to the NBA title in 2008.

"It's an honor to have this opportunity to once again call myself a Boston Celtic," the 39-year-old Pierce said a statement.

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Los Angeles Lakers rookie guard Lonzo Ball will miss the summer league championship game in Las Vegas because of a calf strain.

Ball, the No. 2 overall pick in this year's NBA Draft, suffered a mild right calf strain in Sunday's semifinal win over the Dallas Mavericks, according to Lakers sideline reporter Mike Trudell.

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Houston Rockets owner Leslie Alexander is putting the franchise up for sale after 24 years of ownership.

The 73-year-old Alexander bought the franchise for $85 million in 1993. Forbes valued the franchise in February at $1.65 billion -- eighth-most valuable in the league -- with revenue of $244 million.

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The Memphis Grizzlies signed forward Rade Zagorac of Serbia, the team announced.

Terms of the deal were not disclosed for the 21-year-old Zagorac, who was originally acquired by the Grizzlies in a draft night trade in 2016. He has been training with the Grizzles' NBA Summer League team in Las Vegas.