Roger Federer’s ATP Finals defeat to Alexander Zverev came as a shock to most people.

But perhaps what happened during and after the match was even more surprising and dramatic.

The match ended in a quite resounding win for Zverev against the overwhelming favourite Swiss star.

The score finished 7-5, 7-6(5) in their semi-final showdown, but the result was overshadowed by the controversy surrounding an event that occurred in the second set tie-break.

In the midst of the eighth point, a ball boy dropped a ball which trickled onto the court, and quickly ran to collect it.

The obvious accident happened right in the eye-line of Zverev, who stopped mid-action so that the point could be replayed.

The crowd soon made their feelings quite clear about his actions as the boos began to echo around the court.

Zverev became the antagonist of a show in which the audience were allowed to vent their frustration towards the Germen.

The noise was made worse when Federer lost the tie-break and grew more cynical as the widely admired 37-year-old fell further behind.

After the match, though, Zverev was quick to express his sympathy with his opponent and apologised as the two embraced over the net.

But, the 20-time Grand Slam winner did not see the point of the apology, and told his opponent to “shut up” in the most respectable manner possible.

After having been apologised to, Federer said: "Buddy, shut up. You don't need to apologise to me here. Congratulations on a great match and a great tournament so far. All the best for the finals. And you move on.”

He felt as though Zverev did absolutely nothing wrong in the tie-break.

"He shouldn't be apologising. He didn't do anything about it. He just called it how it was. He felt it affected play.

"There is a rule that if something like this happens, obviously you replay points.

"Should the umpire have explained his case more in that very moment? I mean, rules are rules. Replay the point. Everybody deals with it. You know, I did. We move on.”

Federer was, in fact, most annoyed with the members of the audience booing his competitor. He expressed that it should not happen in his sport.

"It's just unfortunate circumstances. These things happen. Booing, I never like it. We see it in other sports all the time, but in tennis it's rare,” he continued. “So, when it happens, it gets very personal and we take it very direct.”

Finally, Federer hopes that booing will stop in the final and that Zverev can impress in the last stage of the competition.

"I'm sure he won't be booed coming out for the finals, or at least I hope so. It's not his mistake. I think people will be happy to see a good final tomorrow."