Mark Sanchez appeared to be in a world of pain after Saturday's stabbing incident in Indianapolis ... with new surveillance footage showing the bloodied former quarterback holding his torso and struggling to walk right after his altercation with a delivery truck driver.

The 38-year-old ex-New York Jets star was captured on video around 12:30 AM ... right after his violent confrontation that resulted in his hospitalization with multiple stab wounds. Play video content

In the clip, obtained by the NY Post , Sanchez turns a corner to make his way down a sidewalk ... and it's clear he was struggling.

Sanchez's polo has a huge blood stain on his right side ... and he puts his hand up to the area and leans over as he leaves the frame. Play video content

As we previously reported,

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