Craig Tanner netted his third goal against Dundee this season as Motherwell progressed to the William Hill Scottish Cup quarter-finals with a 2-0 victory at Dens Park.
But home goalkeeper Elliott Parish will bemoan his part in Dundee's defeat after allowing Tanner's 30th-minute strike to squeeze underneath his body and making a poor decision for the second goal.
Parish raced off his line as two of his defenders seemed to be dealing with a hopeful ball over the top towards Curtis Main. As he ran out, the ball sailed past him after appearing to come off the head of Kevin Holt, although Main was credited with the goal.
The 56th-minute goal killed off the contest and left Dundee to rue their wastefulness in front of goal, with Sofien Moussa the main culprit.
Former Liverpool defender Steven Caulker watched from the stand after signing for Dundee on Thursday, while Simon Murray was cup-tied.
Tanner was brought into a three-man Motherwell attack after Allan Campbell dropped out with a hamstring strain and he almost set up an opener inside two minutes. Tom Aldred hooked home from close range but Cedric Kipre had been flagged offside while heading Tanner's free-kick across the face of goal.
Moussa headed wide and volleyed over with the first of his two chances before Main came close from 30 yards and Nadir Ciftci glanced a header just wide.
Former Dundee United striker Ciftci was involved in the opener as he laid the ball off for Tanner 25 yards out. The ball bounced invitingly but Parish allowed the volley to slip underneath his body and into the net.
Ciftci, who once bit Jim McAllister in a Dundee derby, was at the centre of a fractious spell of play before the break, being booked for a foul on Paul McGowan immediately after the hosts restarted. McGowan was also carded for his angry reaction.
Ciftci escaped another card following a foul on Mark O'Hara amid strong appeals from the home fans, but Bobby Madden was equally lenient towards Genseric Kunsuga following a wild scythe and a body-check on the on-loan Celtic forward. The Dundee debutant also escaped a claim for a penalty-box handball.
Holt, Glenn Kamara and Darren O'Dea were all off target from decent chances following Dundee set-pieces and Moussa made a mess of another opportunity just after the interval.
O'Hara got Dundee's first shot on target from long range but Trevor Carson pushed the ball over and, when Moussa did get a shot on target after turning Kipre, the Motherwell goalkeeper produced a brilliant stop with his left hand.
Motherwell soon accepted a gift to move two ahead and Carson was not troubled again, although Moussa, O'Dea and A-Jay Leitch-Smith missed decent chances.
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