Scottish Premiership Review: Hearts thrash Motherwell
Igor Rossi's glancing header put the hosts ahead before Osman Sow drilled home a low second and Gavin Reilly's penalty made it 3-0, all inside the first 22 minutes.
Motherwell missed two good chances to get a foothold in the second half and Callum Patterson's goal 13 minutes from time killed any hope of a fightback.
Juanma's fine finish made it five and Arnaud Djoum won and converted a penalty in injury time to seal an emphatic victory.
Dundee moved into the top six after three goals in the first 15 minutes helped them to a 4-2 victory away to Partick Thistle.
Kane Hemmings' penalty put them ahead before captain Gary Harkins pounced on a mistake from goalkeeper Tomas Cerny to make it 2-0.
Greg Stewart bent home a sublime third and Harkins drilled in Dundee's fourth not long after David Amoo's header gave Partick some hope.
Liam Lindsay was sent off for a second booking in the second half to compound a miserable day for the hosts, who netted a late consolation through Kris Doolan.
Dundee's spot in the top six comes at the expense of Inverness Caledonian Thistle, who lost 2-1 away to Kilmarnock.
Greg Kiltie scored from close range for the hosts before Ross Draper netted an equaliser in a first half that had to be halted in order to clear the pitch of snow.
Further stoppages interrupted the second period, but Craig Slater's fine volley ensured a win for Kilmarnock that moves them 14 points clear of bottom-club Dundee United.
They are now also level on points with Hamilton, who battled to a 0-0 draw away to St Johnstone.