The Celtics went for size and strength in the NBA draft, selecting Jared Sullinger and Fab Melo with the 21st and 22d picks Thursday night.

Sullinger, listed at 6 feet 9 inches, 280 pounds, played two seasons at Ohio State, declaring himself an early entry after the team’s final game, a loss to Kansas in the NCAA Tournament last season.

Melo, 7 feet, 255 pounds, was born in Juiz da Fora, Brazil, attended high school in Florida and played two seasons at Syracuse.

“Obviously, we needed to address height,” Celtics coach Doc Rivers said. “The fact that Jared Sullinger fell to us is just fortunate. Last year he would have been a top five pick. All year he was a top-10 pick. The fact that he kept falling to us gives us a rebounder, high IQ player, great passer, and a very good shooter from the outside, gives us some physical force. Fab Melo does the same thing. He has size.

“We like size, we needed size — gives us a chance to work with him. We think he can be a good player.”

Sullinger, 20, scored 1,282 points in two years with the Buckeyes. Sullinger averaged 17.2 points and 10.2 rebounds as a freshman and 17.5 points and 9.2 rebounds last season. A herniated disc, detected during a combine workout in Chicago earlier this month, likely prevented Sullinger from becoming an early selection.

“When the day started, I did not think he would be there at 21,” Celtics president of basketball operations Danny Ainge said. “We got wind, the back issues, he was slipping in the draft. He was projected much higher last week, and so we’re fortunate to get him.

“We were concerned and we did our research on him and we felt comfortable. But there are some issues there. Our medical staff thinks short term and long term there may be some maintenance issues with the back.