Hearts missed a 93rd-minute penalty in a Pittodrie stalemate as Aberdeen's winless run stretched to 11 games - matching their unbeaten streak at the start of the Scottish Premiership season.
The Tynecastle club haven't won at Pittodrie since 2016 and were gifted the perfect chance when Sivert Heltne Nilsen fouled Kenneth Vargas, but Jorge Grant's spot-kick was tipped on to the post by Ross Doohan.
"He's obviously really disappointed, his head's down, but he's got the courage to take it, he wanted it straight away, and he's a very good technician," Hearts head coach Neil Critchley said of Grant.
"I have to give credit to the goalkeeper. I thought it was more of a goalkeeper save than a penalty miss. Jorge has taken penalties before for us and scored. It happens, unfortunately."
Aberdeen had started brilliantly and debutant centre-back Kristers Tobers almost scored after a minute when he scooped a loose ball at goal from a yard out, only for Craig Gordon to deny him.
Topi Keskinen also missed a golden opportunity when Kevin Nisbet's pass put him one-on-one, but the Finn dragged his strike across the goal and wide.
Hearts had the better of it after that but it wasn't until the introduction of Elton Kabangu - making his debut after joining on loan from Union Saint-Gilloise - that they really threatened.
The forward almost scored with his first touch, but his powerful header was tipped over by Doohan. From the resulting corner, Jamie McCart somehow hit the post from a yard out.
Aberdeen are now two points behind third-placed Dundee United, while second-bottom Hearts extend their gap on St Johnstone to nine points.