Image source, Getty Images

Der-dum der-dum der-dum... the dramatic sounds of a heartbeat echo around the arena, putting us all on the edge of our seats as we await for Tomas Berdych and Roger Federer to emerge through the dry ice. 

And then there's a change of pace once the players walk into the darkened arena, the music is turned to full volume and Federer is squinting as the spotlight glares at full wattage on his face.

Jamie Delgado
Former Great Britain Davis Cup player on Radio 5 live sports extra

Piers Newbery
BBC Sport at the O2 Arena in London

Tomas Berdych is appearing at his sixth ATP Finals and goes into tonight's match with a 0-5 record in opening matches. The fact that he is taking on six-time champion Federer does not exactly instill confidence. However, the Czech is a remarkable 5-0 in second matches at this event, so maybe he will come out swinging freely, safe in the knowledge that Tuesday's match is as good as in the bag.  

Tomas Berdych has emerged from his changing room. Asked on Sky Sports how the body's feeling, Berdych replies: "It's feeling good." 

Roger Federer is asked "how's the body holding up?" and the Swiss says "good, pretty good..."

So, there, plenty of juice left in the tanks ahead of this ding-dong. 

You'll be heartened to hear that there is BBC Radio 5 sports extra coverage of this match to accompany these words. To listen to Russell Fuller and co, simply click the 'live coverage' tab on this page. Go for it.

And Tomas Berdych will be a happy man this evening as the Czech Republic have won a dramatic decisive doubles rubber against Russia to secure a fourth Fed Cup title in five years.

In the decider, Karlina Pliskova and Barbora Strycova beat Elena Vesnina and Pavlyuchenkova 4-6 6-3 6-2 to secure a 3-2 win for the Czechs.

The match lasted more than two hours, with Russia gaining an early advantage before the Czech pair fought back to secure victory.

Actually, there's been quite a bit of tennis today and there's good news for British fans, especially those with an eye on the Davis Cup final against Belgium at the end of the month. 

Kyle Edmund won the Buenos Aires Challenger, improving his chances of making Great Britain's squad for the final.

The 20-year-old beat Carlos Berlocq 6-0 6-4 in the clay court tournament, a victory which could move Edmund back into the world's top 100.

Image source, Getty Images

If you're joining us for the first time today, where have you been? We've already watched one match, and that ended in a thumping 6-1 6-1 victory for Novak Djokovic. 

As well as beating Kei Nishikori, the Serb also received his trophy for ending the year as the world number one. His coach Boris Becker has kindly shared a picture on Instagram , externalof team Djokovic enjoying the moment at the O2. 

Image source, Boris Becker

Piers Newbery
BBC Sport at the O2 Arena in London

The distant sound of cow bells can be heard as London's annual November Swissfest is about to get under way. Federer remains the big draw at this and every other tennis event, with the public keen to catch a glimpse of the 17-time Grand Slam champion while they still can. The 34-year-old has absolutely no plans to call it a day any time soon, however, telling BBC Sport: "At the end of the day I love playing tennis in front of sold out stadiums, so it's not difficult for me to stay motivated."

The six-time winner steps out to face a man who has only once reached the semi-finals of this season-ending finale. He's the greatest of the greats, the hot favourite to win this match, but Tomas Berdych could be intent on writing another script. Let's find out. 

Image source, Getty Images