Simon Murray, with a first-half double and ex-Inverness striker Eddie Ofere created a handsome lead before the Highlanders stormed back with goals from Jordan Roberts and Liam Polworth.
Just a few days after their relegation fate was sealed, it was an impressive show of resolve from a group of players mostly set to scatter in different career directions this summer.
But United’s defensive frailties were exposed before and after they were reduced to ten men with a second booking for Callum Morris contributing to the home revival. After a traumatic week at Tannadice, all focus pre-match was on how United, under the temporary charge of assistant manager Gordon Young, would react to the morale-crushing events.
With chairman Stephen Thompson going public on a mass clear-out of playing staff, only five United men had reportedly been told they have a future at the club. Of those, only three started last night – captain Sean Dillon, Murray and Scott Fraser.
After a couple of home forays, United roused about 100 travelling fans by taking a sixth-minute lead. Billy Mckay was sharp enough to nick the ball from Polworth 30 yards out and Murray powering a dipping shot into the right-hand corner of the net.
Just before the break, Miles Storey saw an ambitious chipped shot from 30 yards tipped over by United keeper Eiji Kawashima.
In the very next attack, the penalty paid came in the shape of a second goal for Murray in first-half stoppage time. Amid shambolic defending, Caley Thistle scrambled to clear their lines but when Owain Fon Williams’ outstretched arm blocked a close-range Mckay shot, Murray was sharp to follow-in and slot home.
Ten minutes after the restart, United scored a third with Mckay’s cutback from the left by-line finding Ofere stroking home at the back-post.
But, within a minute, the hosts stormed forward and Roberts cracked a 20-yard shot low inside Kawashima’s right-hand post.
The home cause never looked entirely lost and when the United keeper fumbled a Roberts’ strike after 69 minutes, Polworth raced in to apply a close-range finish.
United were in deeper trouble after 77 minutes, with Morris red-carded after taking his second booking for dragging back Roberts, but they held out.