There was a heated battle between Kyrgios and Nadal at the Mexican Open earlier this week, which saw the Australian come out on top.
It was clear from the offset that the crowd were going to side with the Spaniard and it seemed to affect Kyrgios early on.
However, the tempestuous 23-year-old recomposed himself in the second set to force a deciding third.
And it was clear Kyrgios was feeling it as he hit some incredible winners, showcasing the talents which have seen him tipped to win multiple Grand Slams in the future.
Confidence was clearly flowing through him midway through the third set as he tried, and failed, to utilise the controversial underarm serve.
The match went to a tie-break in the third with Nadal holding three match points, however Kyrgios battled back to clinch the victory.
There was clearly tension between the two players following the result, with Nadal criticising his opposite number for showing a lack of respect for his opponents and the crowd.
Kyrgios was roundly booed by the fans after the result, but the young tennis sensation has found an ally in Federer for his cheeky use of the underarm serve.
“Underarm is definitely a tactic, I believe, especially when guys are hugging the fence in the back.
“From that standpoint, [you] shouldn’t be ashamed if you try it out.
“[You] just look silly if you miss it sometimes. Why not try it?
“The problem is in practice, you never really try it.
“When you come out in the big stage in front of a full crowd, [it is] tricky to pull off.”
“I saw some highlights. The end was epic. [It] had everything, [it was] dramatic.
“It was I’m sure definitely a good match to be in the stadium to watch as a fan.”