The Boston Celtics are expected to announce Monday that they will send the No. 1 overall pick in Thursday’s NBA draft to the Philadelphia 76ers in exchange for this year’s third overall pick and a protected 2018 first-round pick from the Los Angeles Lakers.

A team source confirmed that the Celtics will get that Lakers pick if it falls between Nos. 2-5. Otherwise, the Celtics would get Sacramento’s first-round pick in 2019, which also belongs to the 76ers.

The deal was completed Saturday night when University of Washington point guard Markelle Fultz passed his physical at the 76ers training facility in Camden, New Jersey.

The Celtics, who reportedly are equally enamored with Kansas forward Josh Jackson and Duke forward Jayson Tatum, are still attempting to schedule workouts. Jackson thus far has refused to work out for the Celtics, though he has visited twice with the Lakers, who own the second overall pick.

Talks between Celtics President Danny Ainge and 76ers General Manager Bryan Colangelo progressed rapidly late last week, with 76ers management reportedly putting higher value on Fultz than the Celtics.

Though the Celtics valued Fultz’s overall potential as a lead scorer who can fit in with Isaiah Thomas better than all the other backcourt talent in a draft heavy with point guards, they may value the 6-foot-8 Jackson more for his two-way potential.

Jackson is an athletic swing forward who most believe eventually will be able to play both forward positions in the NBA.

Jackson also projects as a high-level defender who can guard multiple positions. His offensive ability is in a more nascent stage than Fultz’s repertoire, but Jackson is expected eventually to emerge as a floor-stretching threat as well.

Tatum is versatile offensive player who also can play both forward positions.

The Lakers have been widely considered the landing spot for UCLA point guard Lonzo Ball.

Multiple reports, however, suggest a division in Lakers management between their preference for Ball or Jackson.

Fultz has followed a hectic workout schedule.

He worked out for the Lakers three days ago as a follow-up to his Celtics workout, apparently getting enough rest from his right knee injury that caused him to miss five of his last seven games for the Huskies.

“My knee is great. It was just a situation where I had stuff going on in my knee and I took care of it,” he said Saturday.

“It’s been crazy, man, just knowing that the draft is a couple of days away. Unbelievable. I’m just anxious to get to that day, know where I’m going, so I can fully invest into it.”

Philadelphia worked out Kentucky point guard De’Aaron Fox earlier Saturday. On the surface, Fox would have suited the playmaker-starved 76ers nicely.

But management repeatedly has said the team’s point guard of the future is 6-foot-10 Ben Simmons, who will be a rookie next season after missing last season because of a foot injury.

Fox, like UCLA’s Ball, has refused to work out for the Celtics, both players citing their overloaded point guard situation as the reason.