No worries Wawrinka, it's Rafa to the rescue

'Fantastic tennis'

Stanislas Wawrinka of Switzerland celebrates after defeating David Ferrer of Spain in their men's singles tennis match at the ATP World Tour Finals at the O2 Arena in London, Nov 8, 2013. [Photo/Agencies]

Wawrinka may have felt relaxed enough to change channels and search for a movie when Nadal broke Berdych's serve in the opening game on his way to claiming a first set in which he bludgeoned the Czech all over the spectacular O2 court.

Berdych had lost 14 consecutive matches to Nadal, a morale-sapping sequence dating back to 2006, but he is made of stern stuff these days and was not going to give up on his semi-final hopes without at least unloading some heavy artillery.

He broke Nadal's serve to lead 2-0, held his own to love with some booming 135mph deliveries, then broke to love again.

In the blink of an eye it was 5-0 and Nadal was suddenly rattled by the firepower coming his way, casting anxious glances across to coach 'uncle Toni'.

Nadal, who had won only four points in five games, managed to hold serve to avoid an unthinkable bagel against his name, but Berdych belted down more aces to complete a breathtaking set.

Wawrinka need not have worried though.

Nadal gritted his teeth, battled through his opening service game after being taken to deuce and always kept his nose in front in the third set, cranking up the pressure with some ripping forehands.

Something had to give and inevitably it was Berdych, with two double-faults gifting Nadal the crucial breakthrough in the eighth game before he claimed victory, his 74th of a sensational season, with a searing forehand winner.

Berdych, who still has the Davis Cup final against Djokovic's Serbia to look forward to, neatly summed up the difference on the day.

"Those two double-faults gave him that game," he said. "That game I didn't handle well. That's it. That's the difference between the sixth-ranked player and the number one."

Nadal will now have a day to rest and watch six-times champion Roger Federer try to become the second Swiss player in the semifinals by beating Juan Martin del Potro in a shoot-out for runners-up spot in Group B.

"If it's Del Potro, if is Federer, both players know very well how to beat me, in this surface especially," said 13-times Grand Slam champion Nadal, who is assured of finishing the year as world No 1.

"The only way to win the match of semifinals is playing my best match, playing fantastic tennis."