Shaunie O'Neal, Vanessa Lopez Double-Team Shaq

NBA star Shaquille O'Neal is being double-teamed by his wife and his mistress, and not in a basketball manner. Or a sexual manner, for that matter.

Shaq's estranged wife Shaunie O'Neal and enterprising mistress Vanessa Lopez are employing the same investigator to dig up dirt on the big fella.

It all started when Shaunie filed for divorce in November and hired an P.I. to find any info on Shaq's infidelity that could boost her financial settlement.

The investigator discovered Shaq’s multi-year affair with Vanessa Lopez, who's now represented by powerhouse attorney Gloria Allred and suing Shaq.

As if that didn't help Shaunie gain enough leverage, she actually reached out to Allred and Lopez – not to bash them, but to make the affair public!

2-ON-1: Vanessa Lopez and Shaunie O'Neal are hacking Shaq ... legally!

“Shaunie tried to convince Vanessa to go public about the affair before Vanessa did go public,” an inside source said. “And she wanted Vanessa to go to the police too, based on allegations she heard about Shaq harassing her."

“What she discovered about Shaq and Vanessa, gave Shaunie the ammunition she needed to file for divorce and try to get the money she wants.”

Vanessa Lopez eventually came forward, and then did Shaunie one better, claiming Shaq harassed her and even enlisted pals to "shut dat bitch up."

Using the info Shaunie's investigator found, such as Shaq's text messages, she's suing for assault, emotional distress, invasion of privacy and more.

Lopez was disgusted by  info shared by Shaunie, who even believes that someone put a GPS tracking system on her car. Shaunie is taking a no holds barred approach, pushing full steam ahead with the divorce and aiding Lopez as well.

Talk about good team defense turning into transition offense ... or something!