By Craig Turnbull at Fir Park
Hearts missed the chance to cut the gap to second-placed Aberdeen to five points as Motherwell moved up to fourth with a 1-0 win.
Lionel Ainsworth grabbed his third goal of the season on 29 minutes with a low drive from the edge of the box.
Louis Moult struck a post in the second half before Scott McDonald missed a glaring opportunity after dispossessing Prince Buaben on the edge of his own box as Motherwell threatened to score more.
But Ainsworth’s first-half strike proved to be decisive and manager Mark McGhee was delighted with the winger’s contribution.
“It’s funny because I said to a couple of people before the game to look out for Lionel today,” he said.
“Out of all the players that trained really well, Lionel was on fire this week and we were really happy to be putting him in and getting his chance.
“He’s had a difficult, frustrating season but we all believe in him and we all know he’s got a huge amount of talent so we were trying to find a way of allowing him to deliver it.
“Today was maybe the start of him building his confidence in the last five games of the season and maybe next season can be his year.”
Robbie Neilson gave a withering assessment of his side’s display as they failed to capitalise on Aberdeen’s slip-up against St Johnstone.
“We need to come here and perform and we didn’t deserve anything out of the game,” he said.
“Motherwell were the better team: they had a better attacking threat than us, worked harder than us and it just wasn’t acceptable.
“We brought a huge crowd with us and we didn’t do enough to excite them.”