The rivalry between the Boston Celtics and Philadelphia 76ers was taken to a whole new level this summer when Philadelphia signed Horford away from Boston.

The All-Star signing a four-year, $109 million deal with Philly came together rather quickly. In fact, it seemed to be a foregone conclusion that he would return to Boston.

It now looks like the Celtics are accusing their Eastern Conference counterparts of tampering with Horford.

“I don’t know if you heard this, but the Celtics were, from what I am told, one of the teams that kind of stomped their feet about what they felt was tampering,” ESPN’s Brian Windhorst noted on Thursday. “Not with Kyrie, although that looked like it was lined up pretty far in advance, but with Horford.”

The NBA had in the past pushed back big time against tampering. Though, it does seem that things took a back seat in that regard during an otherwise frantic free-agency period around the Association.

As it relates to the Irving situation, it had long been a foregone conclusion that he was leaving Boston for the Brooklyn Nets.

If Celtics general manager Danny Ainge and Co. are upset about Philadelphia “tampering” with Horford, why not accuse the Nets of the same thing?

Either way, it’s highly unlikely that the NBA is going to do anything about this. If Commissioner Adam Silver and Co. do, it would open up a hornet’s nest.