Boss Ian McCall recalled keeper Alan Combe along with Gary Bollan and Craig Easton after last week's last gasp win by Hibs. Charlie Miller again wore the captain's armband.
Motherwell started the livelier side and took an early lead when Pearson bundled the ball into the net from close in, and despite having more chances than the home side United went in at half time a goal down.
United came out fired up for the second period and it was no surprise when Miller equalised with a quality finish after he beat two home defenders in the box. United had more chances before McIntyre netted a truly excellent goal after he mesmerized two Motherwell defenders near the bye-line before squeezing his shot into the net from the narrowest of angles.
Unfortunately some slack defending cost United full points and the side had to settle for a draw when Vaughan scrambled home and equaliser with only a few minutes remaining. The result keeps the Terrors one point ahead of the Fir Park side who meet Celtic on Wednesday evening to play out their game in hand.
Motherwell: Woods, Corrigan, Partridge, Vaughan, Hammell, McFadden, Leitch, Adams, Pearson, Craig (Offiong 69), Clarkson (Lehmann 90).
Subs Not Used: Ramsey, McDonald, Ewings.
Dundee United: Combe, Duff, McCracken (Lauchlan 45), Tod, Bollan, Easton, Miller, Griffin (Wilson 88), Paterson, Lilley (Dodds 76), McIntyre.
Subs Not Used: Gallacher, Latapy.