Rafael Nadal booked his place in the semi-finals of the Barclays ATP World Tour Finals and secured the year-end No 1 ranking with a hard-fought victory over Stanislas Wawrinka at London's O2 Arena.

Novak Djokovic had kept the ranking race alive going into season-ending tournament with a run of 17 straight victories but Nadal still knew two wins in London would be enough to give him the honour for the third time.

It is a remarkable achievement given Nadal did not play a tournament until February after seven months out with knee problems.


Top of the pops: Nadal will finish the year in the No 1 spot for the third time

Top of the pops: Nadal will finish the year in the No 1 spot for the third time



Slipped through: Nadal won the first set after a nervy tie break in London

Slipped through: Nadal won the first set after a nervy tie break in London



Fight: Wawrinka returns the ball against Spain's Nadal during their group A singles match

Fight: Wawrinka returns the ball against Spain's Nadal during their group A singles match

Many questioned whether the Spaniard
would be able to hit the same heights but he has put together one of the
best years in tennis history, winning 10 of his first 13 tournaments.

He
has found the going a bit tougher since winning his 13th grand slam
title at the US Open but was an easy winner over David Ferrer in his
opening round-robin match.

That
meant a straight-sets win over O2 debutant Wawrinka would send him
through to the semi-finals, and the omens were good given he had won all
24 of their previous sets.

Wawrinka
has come close to breaking that run on a few occasions, including in
Shanghai last month, when he had a point to win the opening set.

It was a similar story here but once more it was Nadal who prevailed, this time in two tie-breaks, to win 7-6 (7-5) 7-6 (8-6).



On the bounce: Nadal beat fellow compatriot David Ferrer just 24 hours before his win over Wawrinka

On the bounce: Nadal beat fellow compatriot David Ferrer just 24 hours before his win over Wawrinka

Nadal
was rock solid to start with, not making a single unforced error in the
opening seven games and breaking Wawrinka to lead 3-2 when the Swiss
double-faulted.

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Nadal said: ‘Today it was more important to secure the No 1
at the end of the season. That’s the real thing. During the season I said it
was not my goal but after all the success I had and after what happened last
year, I felt I deserved to be there at the end of the season.


‘I think it is a great effort because I have unbelievable
competitors in front. That makes the year-end No 1 very, very special.


‘It is one of the best things that I have done in my career
to come back to No 1 after three seasons. That’s very difficult in our sport
and after a very important injury. That’s an emotional thing for me, for sure.’


Battle back: The Swiss player did fantastically well to force a tie-break from 4-1 down in the second set

Battle back: The Swiss player did fantastically well to force a tie-break from 4-1 down in the second set

But Wawrinka
has had the best season of his life and he continued to take the fight
to Nadal, earning his reward when the top seed served for the set at
5-4.

Nadal picked up a code violation for taking too long between points and Wawrinka finally managed to breach his defences.

Nadal
was on the defensive again in the tie-break but, as he has so often
done in his career, kept the ball coming back over the net and a stumble
from Wawrinka as he came into the net on set point proved his undoing.

It was no wonder the 28-year-old was frustrated and he smashed his racket three times before flinging it angrily away.

The second set began in a similar fashion, Wawrinka unable to take his chances while Nadal seized his to lead 4-1.

Back came Wawrinka, though, finally taking a break point with a volley that caught the top of the net but landed in.


Shut the door: Nadal closed out his opponents in two tie-breaks despite Stanislas's big effort

Shut the door: Nadal closed out his opponents in two tie-breaks despite Stanislas's big effort

Another tie-break would decide the set and Wawrinka had a chance to level up after fighting back from 4-1 down.

But
Nadal saved the set point expertly and two errors from Wawrinka settled
the match in the Spaniard's favour, even though he won three fewer
points.

Wawrinka, who beat
Tomas Berdych in his opening match, is still in a decent position to
reach the last four ahead of his final group clash with Ferrer on
Friday.

However, he was left feeling aggrieved after his complaints to umpire Carlos Bernardes about illegal coaching from Nadal’s camp during the second set were ignored.

Wawrinka said: ‘We all know, players and umpires, that Toni is always trying to help Rafa. That’s normal. That’s part of the game. But when it’s too much, it’s too much.

‘I didn’t agree with the umpire that he didn’t tell him something or he didn’t give him a second warning just because it was Rafa. Before every point, he [Toni] was trying to coach him. That’s just what happened.

‘It’s nothing against Rafa or Toni. That’s in the rules. Normally the umpire should have done something.’