Josh Jackson says he has some concern about not working out for the Celtics before Thursday's draft. (2:22)

Josh Jackson said he didn't work out for the Celtics because he did not have time to do so after Boston traded the No. 1 overall draft pick to the Philadelphia 76ers.

The Celtics got the No. 3 pick in that deal, which was finalized Monday afternoon. Boston had hoped to work out Jackson on Tuesday, but the workout never happened.

A source told ESPN's Chad Ford on Monday night that Jackson refused to work out for the Celtics without an assurance the team would hang on to the No. 3 pick and that he was the top player on their draft board.

In a pre-draft interview Wednesday with ESPN, Jackson confirmed he did not work out for Boston.

"They did a little bit of moving around with their pick," Jackson said. "I felt like they made it pretty clear who they were going to draft with the No. 1 pick, so I didn't really feel like it was worth either of our times for me to work out with them. But then when they, you know, did the flip and went to No. 3, by then it was too late."

Jackson was asked if he was concerned whether the decision to skip a Celtics workout would affect him in Thursday night's NBA draft.

"It could, it may or may not," he said. "But like I said before, I'm just happy to be here. Wherever I end up Thursday, I'll be happy."

After trading the pick Monday, Celtics president of basketball operations Danny Ainge told reporters that the organization thinks there is "a really good chance the player we'll take at 3 is the same player we would have taken at 1." The Celtics worked out Duke's Jayson Tatum on Monday.

The Sixers are expected to draft Markelle Fultz with the No. 1 pick. ESPN's Chad Ford has Jackson going to the Celtics at No. 3 in his final mock draft.

Sources told ESPN on Tuesday that the Knicks, who have the eighth pick, and the Bulls, who are slotted at No. 16, both have shown interest in Jackson. Both New York and Chicago likely would have to trade significantly up in the draft to pick the former Kansas star.