Dundee United's impressive home form continued as a Darren Dods header 12 minutes from time sealed the points against Motherwell at Tannadice.
Darren Dods races away to celebrate after his crucial winner
Dods nodded a Barry Robson corner into the net in a match that was always likely to be settled by a single goal.
A disappointing Motherwell did not reach the performance level that saw them take a point from Rangers.
It leaves United clear in fourth place and undefeated at Tannadice, with their fifth home clean-sheet in-a-row.
Dundee United made two changes from the side well beaten at Celtic Park the previous week with Christian Kalvenes and Steven Robb replacing the benched David Robertson and Jordan Robertson.
Jon Daly took his first tentative steps back to first-team action with a place among the substitutes.
For Motherwell it was the same again from manager Mark McGhee as he named the side that drew 1-1 with Rangers.
The home side had lost their previous two matches but they began the brighter of the two teams.
Morgaro Gomis and David Clarkson battle for possession at Tannadice
Prince Buaben and Barry Robson both went for goal early on with Jim Paterson forced to make a last ditch block on a Noel Hunt effort from six yards out and deny the Irishman a simple tap-in.
Graeme Smith was also called into action to turn a Hunt shot wide as the Tangerines looked for first blood.
Motherwell stemmed the early tide and began to relax on the ball as Willo Flood went into the book for a scything tackle on Ross McCormack.
Despite this, there seemed to be a lack of energy from the visiting midfield as United dominated this area of the park but the defences could not be breached as half-time arrived.
The Steelmen immediately improved as the second-half got underway with Stephen Hughes seeing a shot inside the area blocked by Morgaro Gomis.
This spurred McGhee's men on and Ross McCormack curled a 20 yard effort just over before David Clarkson missed from just outside the area.
Despite the pressure from the visitors - who had not won at Tannadice since 2004 - it was the home side who got their noses in front with 12 minutes to go.
United skipper Robson swung a corner in from the left and it was met by Darren Dods who nodded them in front against the run of play.
Motherwell upped the tempo as they tried to get themselves back into the game but United held on to keep their home record intact.
Dundee Utd: Szamotulski, Dillon, Wilkie, Dods, Kalvenes, Flood, Bauben, Gomis, Robson, Robb (Jordan Robertson 76), Hunt. Subs not used: McLean, Kerr, Daly, David Robertson, Cameron, Kenneth.
Goal: Dods 78.
Motherwell: Graeme Smith, Quinn, Craigan, Reynolds, Paterson, McGarry (O'Donnell 88), Hughes, Lasley, Clarkson (Grabban 84), Porter, McCormack (Darren Smith 84). Subs not used: Meldrum, Mensing, Fitzpatrick, Kinniburgh.
Ref: S Finnie