The O2 is empty and there are no more coins left to put in the meter, which means we must wrap up this live text commentary. There will be more from us this evening, however, as Stan Wawrinka takes on Marin Cilic at 20:00 GMT. Thanks, as always, for your contributions. Bye for now.

John McEnroe, who has joined Sue Barker and Tim Henman, in the studio, is full of praise for Nishikori.

"I don't understand these big guys. Nishikori, mentally he's so strong right now, he's giving you different looks, he came to the net, hit some serve volleys - memos to other top players who are six inches bigger than him."

Novak Djokovic and Kei Nishikori have played each other on four occasions, with both enjoying two victories each. Nishikori, of court, surprised many by beating the world number one at this year's US Open semi-finals.

John McEnroe on ending the year as world number one: "For me, it meant more than the Slams. In retrospect I sort of wished I'd taken the Slams more seriously. I took great pride in that (ending the year as world number one). One year, I finished number one but didn't win any majors. It's not that easy to finish number one, regardless if you win a Slam or not."

Tim Henman
Former British number one on BBC Two

Image source, Getty Images

"When you're playing indoors with perfect elements, they can elevate their games. Some of the tennis we've seen from those two (Djokovic and Federer) has been as good as I've ever seen. I'm keeping my fingers crossed we see Federer versus Djokovic in the final, that would be a fitting end."

Denise in Wiltshire: It's such a shame how so many people are so quick to slate Andy Murray when he loses a match. I wonder if this these are the same people who voted him Sports Personality Of The Year In 2013.

We've also been asking you this afternoon how Andy Murray should react after last night's defeat:

Phil:, external Murray shouldn't panic. Fed struggled last year & has bounced back superbly. Add some variety & net play to an already solid game.

Tim Henman
Former British number one on BBC Two

On TV, the chat has returned to Murray. Here's what Henman has to say:

"It will be an interesting off season. He's talked about getting a super coach involved. I thought Mats Wilander, at once stage, would be a good addition. It'll be interesting to see if he can add another dynamic to his game next year."

Djokovic poses for the cameras after exchanging handshakes and backslaps with the likes of McEnroe. The photographers don't have to ask him to smile.

Djokovic has yet to be beaten since becoming a father to baby Stefan on 22 October.

"I got married, became a father recently and it's the most beautiful thing in the world and to be able to stand next to this trophy and to have the crown for all the achievements in this 12 months, it's very fulfilling and it's a joy," says Djokovic.

Asked if he will celebrate this evening, Djokovic replies: "I don't think so, the tournament is not over. I have maybe a few hours of celebration and then turning back to semi finals and preparing for it."

Image source, Getty Images

The man of the moment, Djokovic, jumps up from his chair but is being made to watch a video montage of his year while the big-eared silver trophy twinkles in the spotlight in front of him.

Finally, the world number one is allowed to take his prize and he lifts it skywards, kissing the sought-after silverware.

Tournament organiser Chris Kermode steps onto the court to present Novak Djokovic with the year-end world number one trophy. There are also special guests, it's a bit like Surprise Surprise, as John McEnroe, Boris Becker and Mats Wilander appear.

"Definitely one of the best," says Djokovic of his performance. "Obviously I hoped I could continue the way I played in the first two matches. It's been a long year, a long season, it's an incredible achievement and I want to thank my team and my family and all the people who supported me.

"I'm aware that being number one in the world is the biggest challenges a tennis player can have. It's an incredible feeling and I'm very happy.

"I've been playing since I was four. I was very fortunate to have very knowledgably people, the people who believed in me and believed in my talent."

Image source, Getty Images

After the first game of the first set, when he broke Berdych, it felt almost inevitable that Djokovic would win, and do so comfortably. Djokovic's semi-final opponent? Kei Nishikori. "It won't be easy," says Djokovic.

Tim Henman
Former British number one on BBC Two

(when asked what Kei Nishikori's tactics should be if he wants to beat Djokovic in the semi-finals)

"I'd be looking at food poisoning first..."

Andrew Castle
BBC tennis commentator on BBC Two

Image source, Getty Images

"The celebration is for the year-ending number one position. It's like winning the league, and it's the result of a lifetime's work for him and his team. A tremendous sporting achievement."

Here we go. The final game of the match. The two-time defending champion closing in on his 30th consecutive victory indoors. He pulls Berdych this way and that from the baseline, the bedraggled Czech unable to negotiate the barrier and Djokovic has three match points. He needs just the one - Berdych wide. Djokovic undefeated in this tournament, dropping just nine games in three matches, and he will end the year as world number one.

At 30-0 the pair trade blows from the baseline, with Djokovic pulling the trigger with a jaw-droppingly good backhand winner down the line. The Serb pulls Berdych towards the net with a drop shot - but Berdych covers the ground quickly, gently volleying beyond the Serb to hold to 15.

Andrew Castle
BBC tennis commentator on BBC Two

"For Djokovic, to have lost only five games in his first two matches against Cilic and Wawrinka is amazing. He's a game away from another milestone."

Berdych's feet aren't moving in unison and the 6ft 5in Czech looks flat-footed on the baseline. Another simple hold for Djokovic, concluding with a cool ace. The Serb clenches his fists, he knows victory is in sight.