Hearts manager Craig Levein hailed his young central defence as the cornerstone to the victory that took them five points clear at the top of the Ladbrokes Premiership.
Zdenek Zlamal made a good save from Curtis Main as Motherwell pressed in the early stages at Fir Park but Hearts never looked back after Steven Naismith capitalised on a slack pass from Carl McHugh to net the only goal in the 28th minute.
Zlamal made another decent stop from McHugh just after the break but Hearts otherwise soaked up the pressure and could have added to their lead.
New Scotland international John Souttar, 21, and 20-year-old on-loan Burnley defender Jimmy Dunne repelled a number of balls into the box and Hearts looked even more comfortable when debutant Clevid Dikamona came off the bench to join him in central defence.
Levein said: “I thought this was going to be really tough and our base strength was our defending. The two young centre-backs were amazing. I watched the Rangers game here a few weeks ago and the strike force of Motherwell caused the Rangers centre-backs all sorts of problems.
“But Bobby (Zlamal) had one decent save to make and other than that we defended magnificently, and that was the platform for our victory.
“Second half, although they bombarded our box with high balls, when we won the second ball, if we picked the first pass we were almost running the length of the field to get an opportunity to score. Three times we should have squared the ball for a tap-in but we can work on that in training.”
Levein is set to add to his table-topping squad by signing free agent Sean Clare, a 21-year-old midfielder who left Sheffield Wednesday in the summer.
“It’s been quite complicated,” Levein said. “He’s a Sheffield Wednesday player essentially because he is still subject to training compensation, and we are just trying to get that whole thing sorted out. I believe the paperwork is nearly done and he should be with us Monday. And I can’t tell you how excited I am.”
Motherwell suffered a double blow following McHugh’s under-hit ball back to his goalkeeper as Trevor Carson suffered a bad ankle injury after being closed down by Uche Ikpeazu.
Former Carlisle and Walsall goalkeeper Mark Gillespie came on for his league debut and made good stops from Dunne and Demetri Mitchell.
Manager Stephen Robinson said: “It’s a huge blow. He is going to be out for a period of time, I have no doubt bout that, looking at the state of his ankle.
“We have got Mark, we made a conscious decision to have two number one goalkeepers. So Mark will get his chance and we will just have to see where Trevor is.”