Ten-man Hearts overcame a stubborn Dundee to claim a narrow win and restore their six-point lead in the Scottish Premiership title race.
Derek McInnes wants to make "every game count" in their push to end the Old Firm's lead dominance, and Alexander Schwolow was quickly called into action to deny Billy Koumetio as Dundee looked to extend their winning run to four.
Hearts scored with their first shot on target, but not without frustration from the hosts. Claudio Braga drilled a low shot in off the post from 20 yards as Dundee claimed the ball was rolling as Cammy Devlin took the quick free-kick in the build-up.
Schwolow brought down Tony Yogane outside the box with half-time approaching. The goalkeeper thought he had been saved by the offside flag, but the referee showed him red after being sent to the monitor.
Craig Gordon took his place in the Hearts goal for the first time this season and immediately denied Dundee. The 43-year-old then pulled off a world-class save in stoppage time to keep their title charge on track.
Gordon shows age is just a number
Craig Gordon told Sky Sports just last week he was "one step from getting a chance" and the red card gave him that chance to prove his worth to the league leaders and to Scotland head coach Steve Clarke as the World Cup approaches.
Dundee did start brightly with Schwolow palming Koumentio's header clear just two minutes in.
Hearts, though, took control and went in front as Braga fired home via the post from the edge of the box.
The goal came from two simple forward passes, but Dundee were furious it was allowed to stand, after Devlin took a free-kick some distance from where the foul took place.
They were given a chance to get back into the game when Schwolow took out Yogane on the edge of the box, with referee Ryan Lee sending the keeper off and Gordon returning to the Hearts line-up after a long absence.
But they couldn't make their extra player count - Hearts defence stood firm after the break, as Gordon saved from Koumetio and Drey Wright.
In the 94th minute, Emile Acquah looked certain to level with a header but Gordon sprung to his left to push the ball to safety with an unbelievable save.
'One of the best I've ever had'
Hearts goalkeeper Craig Gordon speaking to Sky Sports:
"I think that's probably up there with one of the best I've ever had.
"So important for the team to keep our run going. Three points was huge for us.
"Everybody had to dig in so much second half to defend the box at times and yeah, it's a really good save and so late in the game, so important for us.
"You've just got to be ready. I've felt good in training all week. We played a bounce match during the week and played well in that, so I felt as if I was ready to come in and play.
"It's not quite the same when you get out there, but I felt really good going in there and thankful to keep the clean sheet second half.
"It's on to the next one. We need to keep winning these matches, difficult matches away from home.
"They've been on a really good run, so for us to come up here, get the 1-0 grind out at times, that's what it's going to have to take.