Cooper Flagg of Newport, Maine, is seen at the training camp for the U17 World Cup national basketball team. Credit: Courtesy of USA Basketball

Former Nokomis High School of Newport star forward Cooper Flagg and his United States teammates were finally tested in the FIBA Under -17 World Cup Basketball Tournament in Malaga, Spain, on Friday during their quarterfinal against Serbia.

But Flagg, one of just three 15-year-olds on the Team USA roster, had his best game of the tournament as the Americans beat Serbia 106-80 to advance to Saturday’s semifinals where they will play Lithuania in a battle of undefeated teams.

Flagg scored 18 points, grabbed 11 rebounds and blocked three shots, all game-highs, and he also dished out four assists and made three steals.

The 6-foot-8 forward shot 7-for-15 from the floor, including hitting his only 3-point attempt.

He played 23 minutes and 40 seconds.

Of his 11 rebounds, five came on the offensive glass and six were on the defensive end.

His 18 points represented his best output of the tournament. His previous high was 12 points in last Sunday’s 88-55 victory over Slovenia.

Flagg was one of six Americans in double figures. 

Koa Peat had 17 points, Asa Newell netted 12, Johnuel Omari Fland scored 11 points and David Castillo and Ronald Holland chipped in with 10 apiece.

The Americans had won their previous four games by an average of 53 points but the Serbs gave them a battle. Team USA led by just 12 at the half before slowly pulling away in the second half.

Team USA is 5-0 and has now won all 42 games it has played since the tournament’s inception in 2010. It has won the five previous events.

Lithuania, also 5-0, advanced to the semis with a 73-44 victory over Poland.

Following the tournament, Flagg will play for the Maine United 15-Under team in the Peach Jam National Tournament on July 17-24 in North Augusta, South Carolina.

The Maine United team went 7-1 in two Nike Elite Youth Basketball League tournaments to earn a spot in the Peach Jam Tournament.

The son of Ralph and Kelly (Bowman) Flagg and his twin brother Ace led Nokomis to its first state Class A championship this past season and he was the first freshman to earn Maine’s Gatorade Player of the Year award.

He has already received scholarship offers from Duke, UCLA, Michigan and Iowa.

Flagg, chosen the third best player in the freshman class by ESPN, will attend the highly regarded Montverde Academy in Florida this fall along with Ace.