Such an exciting finish could not have been predicted in the opening minutes as barely an angry glance was exchanged in what resembled a training match.
But the fans got value for money in an intriguing finish culminating in that late penalty.
Hearts started brightly with a great move down the right involving Laryea Kingston and Andrew Driver. The ball was eventually switched to Andrius Ksanavicius, but he dragged his shot wide.
Celtic hit back through Jiri Jarosik's 25-yarder that drifted inches wide before Christophe Berra climbed at the back post to nod Kingston's cross over the bar.
But it was poor stuff from both sides and the game lacked passion and energy.
However, Driver had the Hearts fans off their seats with a 25-yard free-kick that was just past the upright and the half ended with a chance at both ends.
Basso dropped Paul Hartley's free-kick but Steven Pressley couldn't capitalise.
And then Christian Nade burst past Darren O'Dea to cut back for Kingston who blasted over from 15 yards.
It took a goalkeeping howler to break the deadlock after 73 minutes.
Hartley's 25-yard free-kick should have been an easy take for Basso, but he spilled the ball into the path of Scott McDonald and the prolific Aussie made no mistake from eight yards.
The Hearts keeper did redeem himself with a great save from Aiden McGeady, but he would be the happiest man at Tynecastle when Hearts grabbed an injury-time equaliser.
Artur Boruc denied Ksanavicius with a stunning save and, as the ball came out, Caldwell bundled into the back of Ibrahim Tall to concede a needless penalty.
And Hearts top scorer Velicka stepped up to thump home the spo- kick for his third goal in two substitute appearances against Celtic.