Both sides fielded unchanged sides after good away wins at the weekend, but the match was slow to start.
There were only a couple of Cillian Sheridan shots - both dragged wide - to speak of in the opening 20 minutes.
It took until the half-hour for the first real shot on goal and it was almost an opener for Well's Stephen Hughes.
After the ball broke to him on the edge of the area, the lanky midfielder's shot rattled the bar and rebounded to safety.
All Hearts could muster in a scrappy first half was a 25-yard shot by full back Lee Wallace but his left-foot strike was pushed round the post by Graeme Smith.
The second half sparked into life just five minute in and it was poor Motherwell defending that cost them the opening goal.
Long throw specialist Robbie Nielson saw his delivery flicked on by David Obua and with the Well defence napping, Andrew Driver stole in to score a close-range header.
The visitors' first shot on target came as the match neared the hour mark as David Clarkson did well to find the target from long range but the assured Janos Balogh dealt with it comfortably.
Five minutes later and Driver almost grabbed his second goal. The young winger showed his pace on the break as he beat Stephen Craigan but the angle was tight and his shot found only the side-netting.
Maros Klimpl had Well's next chance but again Balogh was equal to it.
This chance came just before the visitors lost captain Craigan to a nasty head knock, with Darren Smith coming on in his place.
That disappointment was not to last as the Lanarkshire side equalised in the resulting phase of play in 75 minutes.
The impressive Hughes blasted a fine left-foot shot from 25 yards which bounced before finding Balogh's left-hand corner.
The match looked certain to end level before Palazuelos struck and Well could not find a last-gasp equaliser.