This is the emotional moment a 19-month-old toddler with one leg climbed a staircase entirely on his own for the very first time — while his stunned parents watched in disbelief.

Little Lucas Bobakov was filmed carefully making his way up nine stairs step-by-step, refusing to let his disability slow him down.

As the determined youngster finally reached the top, his mother Leeza Bobakov, 27, could be heard celebrating with excitement while his father Dennis, 29, stood closely behind him in case he needed help.

But in a moment that melted hearts online, Lucas simply looked calmly at his mum as though his incredible achievement was completely ordinary.

His proud mother later described the moment as “nothing short of a miracle.”

“I was bursting with pride,” Leeza said. “Lucas just got straight to it and climbed the stairs completely by himself.”

“To see our baby, who only has one leg, doing things many toddlers struggle to do at his age is amazing. He’s such a strong little boy.”

The family, from Philadelphia, Pennsylvania, have faced extraordinary challenges since before Lucas was even born.

During pregnancy, complications caused Leeza’s placenta to rupture, leading Lucas and his twin brother Peter to develop twin-to-twin transfusion syndrome — a dangerous condition affecting blood flow between twins.

Doctors warned the family the babies might not survive after they were delivered prematurely by emergency C-section at just 30 weeks.

Lucas received too much blood flow in the womb, which caused a clot to form in his leg. Tragically, the damage led doctors to amputate the limb when he was only three weeks old.

Meanwhile, his twin brother Peter was born deaf after suffering reduced blood supply during pregnancy.

Despite everything, both boys survived — something their mother says she never takes for granted.

“There isn’t a single day that passes where I’m not thankful my boys are here,” Leeza said emotionally. “They are my survivors, my little bionic boys.”

And Lucas has continued proving his strength ever since.

The determined toddler began crawling at just six months old before learning to walk using a prosthetic leg shortly after turning one.

The recent staircase moment happened while visiting his cousin’s house, as the family does not have stairs in their own home.

For his parents, however, the simple climb represented something far bigger than nine small steps.

It was another reminder that their little boy refuses to let anything define what he can achieve.