Dundee end their losing run of 4 games and the manager heaped praise on the strike partnership of David Clarkson and Greg Stewart.
Hartley said "They worked well as a pair and it's something we worked on all week,"
"The front two got good service and their movement caused the Motherwell back four all sorts of problems."
The manager added: "[Stewart] came from Cowdenbeath, where he was part time, and it took him about six weeks to get his fitness up because he wasn't used to full time football.
"He's got a great touch and great vision, he's a good team player and Clarkson has great experience - you saw that with his goal."