Welcome to our LIVE coverage of this semi-final clash in the ATP World Tour Finals at the O2 in London.

Remember - we will be covering the final tomorrow at 5.30pm. Make sure you return for what promises to be a cracker!

TSONGA 7-5 GAME SET AND MATCH! The first point is a thriller as Tsonga backhands wide along the line. Almost a lovely winner. He wins the next two points as Berdych goes wide, followed by a serve of real venom. On second serve he serve-volleys for the first time tonight, dropping it delicately over the net for three match points. What a time to suddenly return to your usual game. ACE! What a way to do it! His first World Tour final!

TSONGA 6-5 BREAK!! Deuce then - and off second serve Tsonga kicks a wicked return, Berdych makes it with interest and Tsonga can't angle a crosscourt winner so puts it back. But Berdych misses, into net! Second serve again and after a rally there's an unforced error as Berdych nets! What a mistake! Tsonga serving for a place in the final against Fed!!

TSONGA 5-5 A fourth double-fault of the second set for Berdych and it's 15-30... What could have been an ace clipped the net according to the machine, which bleeped a touch early for me! He does really well to win the point with a volley and a smash after 'doing a Tsonga' and zipping to net. But what a shot from Tsonga, double-handed stroking the net and flying away! From nothing, such power on the strike! Break point! Great return follows but an even better attack from Berdych and Tsonga nets.

TSONGA 5-5 Cracking hold under pressure from Tsonga with a killer forehand into the corner. This could well go to a tiebreak.

TSONGA 4-5 Berdych is up for it all of a sudden, a serve-forehand combi too good for Tsonga. The Frenchman has been in charge, surely he can't collapse now? Well with Tsonga prone Berdych somehow pumps wide. Deary me, shocker. 15-15. Just a blip though as he kicks in with a few strong serves to 40-15. But a double-fault follows and another and it's deuce! Deary me! But a ferocious serve and another for a hold.

TSONGA 4-4 BREAK BACK! But hang on - some dodgy first serves from Tsonga and Berdych has a sniff at 40-15, Tsonga clipping a pass wide after a nice drop from the Czech! Two break points! The first is snatched back by Tsonga but a killer return sees the Frenchman slide into a low forehand into net! The break is Berdych's! Nerves from Tsonga perhaps.

TSONGA 4-3 BREAK! Vicious forehand again from JW which Berdych can only skew into the mesh. And another draws an error from Berdych, 15-30 now. Then with a chance of a winner, Berdych pumps it wide! Two break points! First serve into the net, the second is wide and it's a double-fault to break!!

TSONGA 3-3 A mighty forehand from Tsonga, who rushed to net just in case. Berdych challenges a Tsonga ace... Just in. 30-0. And he slips one wide of Berdych for 40, making it a love hold with another ace. Superb from Tsonga.

BERDYCH 2-3 The neutrals are cheering every Berdych point now, despite Tsonga being so popular in London. Why? They want their money's worth, the full three sets. Berdych pings a deep forehand right into the corner, one of his faves, then Tsonga uncharacteristically hits long. Berdych holds with a kicking serve.

TSONGA 2-2 First serve is wide - just - but Tsonga takes the first point with a punishing drive after Berdych clipped the net. Big first serve that Berdych can't return, then game point with another. But a double-fault and it's 40-15. Game as Berdych goes long following a serve-forehand combo from Tsonga.

TSONGA 1-2 'Allez allez!' yells JW as Berdych earns game point, which he takes after a lovely rally of net volleys from both men, Tsonga stranded in the end as the Czech drifts the winner away.

TSONGA 1-1 Tsonga hammers a big forehand from deep once more. It seems like he's trying to spend as much time at the baseline as possible to reserve his best volleys for the final. He makes a great backhand after hurling himself across court but Berdych is wise to it with a drop shot. The large Czech contingent liked that. Then just long from Tsonga as he battles in vain to keep in some Berdych smashes. But a forehand cross levels from Tsonga, superb shot once more.

TSONGA 1-1 Big double-hander to the corner from Tsonga which Berdych can't make. More baseline work from JW. Big serve to follow, and it's game point in no time as Tsonga pumps a killer forehand pass off second serve. No hold to love for the big man as he challenges a shot called in by Berdych that seemed to land long... no, in. 40-15. Umpire warns the crowd for yelling. He holds with a swift forehand into the corner after a stumpy return from Berdych.

TSONGA 0-1 Long from Berdych after Tsonga stays in the rally via the net, and it's break point again for Jo-Wilfried! He loses it as a backhand lob lands well long - Berdych's volley forcing that - but another unforced error and it's break point again... The first serve nets... but a huge second serve sees Tsonga return into net. Brave. Great serve again and advantage Berdych, and a big hold as Tsonga pumps the return long.

TSONGA 0-0 Berdych starts his first service game with intent, Tsonga unable to return, but his next serve is long and the second serve returned with a cute backhand slice, Berdych striking his forehand long. He kicks another forehand long, his ninth such error, but he levels with his next first serve. A booming forehand into the corner gives him game point but the big Czech nets poorly and it's deuce.

TSONGA 6-3 SET! Weirdly for Tsonga he opts to hang out at the baseline, a yard behind it even, but he takes the first point as Berdych goes long. Berdych challenges the next serve but it was right on the line, three set points as Berdych can't return in, and a classy love hold to close out the set as Berdych goes long following some tasty slices by the Frenchman. Allez Ali!

TSONGA 5-3 An ace puts Berdych 30-0 up but Tsonga pings a lovely return that catches Berdych off guard. Good change of pace from Berdych as he kicks it wide of Tsonga, who can only spin his crosscourter wide. On second serve at game point, Tsonga can only net the return and Berdych holds. Tsonga serving for the set.

TSONGA 5-2 Can Berdych respond? Tsonga is at his acrobatic best to force Berdych wide, he's 40-up now after Berdych returns weakly to net and he holds to love with a similar effort. Superb stuff from Tsonga as Berdych has to serve to stay in the set.

TSONGA 4-2 BREAK! The Frenchman moves 30-0 up off some poor sliced second-serves from Berdych. He pulls one back with a soft volley after some strong running from Tsonga, but a super return and it's two break points to Tsonga... The first is eaten up with a speedy first serve that Tsonga can't return over the net, but he has to second serve next and goes long to the back of court! First blood Tsonga!