Crook tries stealing cash from register. But 120-pound clerk—trained in martial arts—isn't playing.

Ebrahim Gawargi isn't terribly imposing at 5 feet, 7 inches tall and just 120 pounds — but he's not to be messed with.

One guy learned that the hard way Tuesday night after entering a Mobil gas station store in Norwood, Massachusetts, where Gawargi works as a clerk, WFXT-TV reported.

Surveillance video showed the hooded man trying to grab money from an open register as Gawargi was counting cash.

Image source: WFXT-TV video screenshot

But he wasn't about to let the intruder get away with anything.

The clip showed Gawargi immediately fighting back and exchanging punches with the crook:

Image source: WFXT-TV video screenshot

Then hopping over the counter:

Image source: WFXT-TV video screenshot

Slamming him into shelves:

Image source: WFXT-TV video screenshot

And bringing him to the floor before finally subduing him with a sleeper hold, the station said.

Image source: WFXT-TV video screenshot

How'd he do all that?

As you might have guessed, Gawargi knows a thing or two about self defense. In fact, he told WFXT he trains three to four hours a day at Connors Martial Arts Academy in Norwood.

Image source: WFXT-TV video screenshot

"I just do it to have fun ... just come to training, get some fun over here," he told the station, adding that he started training  two years ago when he moved to America from Egypt.

Image source: WFXT-TV video screenshot

John Connors, a teacher at the academy, told WFXT that Gawargi is an "excellent student" who "takes his training very seriously" and is "very determined" and "very, very scrappy."

Image source: WFXT-TV video screenshot

"So I'm not surprised he got the best of the guy," Connors added to the station.

For Gawargi, there was no choice.

"When he attacked me I had to do something," he told WFXT, adding his assailant "grabbed my hand; I had over six hundred dollars in my hand."

Image source: WFXT-TV video screenshot

What about his sleeper hold?

"I didn't want to kill him," Gawargi told the station of the intruder he subdued in the video. "I needed to let him breathe, [but] when he kept moving I gave it more pressure to let him sleep again."

Image source: WFXT-TV video screenshot

A customer outside the store saw the altercation and called police, WFXT said.

What happened to the would-be robber?

John Benedict, 46, was being held on $5,000 bail, the station said.

Norwood Police Chief Bill Brooks told WFXT that he would prefer that robbery victims just hand over what's demanded and then call police but noted that "this was a little bit unusual because of the skills of the clerk."

Gawargi got two days off after the dust-up, the station said.