Superior serving, mental improvements help Novak Djokovic to 20th Grand Slam title

WATCH: Djokovic speaks with the press following his sixth Wimbledon victory on Sunday.

Novak Djokovic keeps adding more Grand Slam titles to his collection, and it's no coincidence that he also keeps adding more weapons to his game.

The 34-year-old, who has also captured the Australian Open and French Open this season, won a record-tying 20th Grand Slam by defeating Matteo Berrettini to win Wimbledon.

"I feel like I'm probably the most complete that I've been as a player right now in my entire career," he told press.

The most noticeable improvement has been his serving, especially at Wimbledon. And the Serb's enhanced delivery was on display during the tournament. He led the field in points won when getting his first ball in, even beating the big-serving Berrettini 79 percent to 76 percent in this category.

"He's really precise. He's really hitting the line when he wants to. This is something, especially on this surface, really important," said Berrettini.

I feel like I'm probably the most complete that I've been as a player right now in my entire career. Novak Djokovic

That shot was the specialty of coach Goran Ivanisevic, who joined the team a few years ago and has emphasized going bigger in the big moments. It's now also backed up by Djokovic's increased effectiveness going forward. He came to net 33 times against Shapovalov in the semifinal, even serving-and-volleying a few times, and 48 times against Berrettini.

Though Djokovic isn't likely to become a regular net rusher, Ivanisevic says it's another big improvement.

"But Novak's volleys [have] improved a lot. He's a not bad volleyer when he wants to come to the net... When he's against Shapo, he was serving [and volleying] a lot because he felt great at the net," he said.

And that's on top of Djokovic's established strengths—his movement and baseline game—which are quite enough, by Berrettini's assessment.

"I think first of all, obviously the way he neutralized my weapons, my serve and my forehand. The way he covers the court," he said. "It's something that I never experienced."

But Djokovic's own choice is more on the mental side.

"I felt like from 15 years ago to today the journey that I've been through has been very rewarding for every segment of my game, and also my mental strength—the experience, understanding of how to cope with the pressure in the big moments, how to be a clutch player," he said. "That's probably, if I have to pick one, the one that I would as the highlight of my, so to say, improvement."

Along with the title, he also keeps his No.1 ranking.