Arzani and Cahill – who is literally twice the age of the Melbourne City teen prodigy – tussled in a tackle towards the end of training yesterday.

As the two challenged for the ball, Cahill appeared to poke Arzani in the eye with his outstretched hand attempting to keep the 19-year-old at bay.

But the persistent youngster wouldn't give up and still tried to get his foot on the ball, but ended up tangling up legs with Cahill.

The evergreen 38-year-old crashed to ground with pain apparently etched on his face, swiftly followed by Arzani.

And as Cahill grabbed at his thigh in apparent agony, Arzani looked every bit the naughty teenager caught while up to mischief.

He looked to coaching staff for reassurance as he waited to see if Cahill would recover, and wiped his own weeping eye with his training bib while Cahill glared at him.

He helped Cahill to his feet before Cahill finally let rip a grin – and proved his fitness with a remarkable strike on goal that left Massimo Luongo in awe!

Playtime for the teen was not over yet though, with keeper Brad Jones targeting him for some wrestling practice, eventually pinning him down to the ground by the head.

But Arzani was keen to prove his own fitness with a spectacular bit of control in mid air, before Cahill took him to task yet again in a shootout, which ended with Cahill smashing Arzani with the ball and joking about his ability with his left foot.