Rafael Nadal has a chance for redemption

— -- Rafael Nadal traveled to London to play in the ATP World Tour Finals seeking redemption in a year gone horribly wrong.

Now, he's put himself in a position to get what he came for in the most appropriate way imaginable: with wins over one (or perhaps both) of his great career rivals, and triumph at the only major event he has never won.

Nadal will play Novak Djokovic in the semifinals of the year-end championships, with Roger Federer a potential final-round opponent for the winner. That Nadal is fired up and eager to end his tennis year with a bang was obvious Friday in his final round-robin match.

David Ferrer is the last guy anyone would want to have to play if the person had somewhere to go or someone to meet. He's a grinder with a talent for dragging everything out.

With a semifinal berth assured, Nadal might have been tempted to throw in the towel after Ferrer unexpectedly roared back from an 0-3 deficit to win a first-set tiebreaker. Instead, Nadal played like a man with a point to prove. He finally found confidence, and wasn't going to let it go, try to save it for tomorrow, risk losing it. Not for anything in the world.

Nadal ended up winning the longest match of the tournament, pinning pesky Ferrer to the mat in 2 hours, 37 minutes, 6-7 (2), 6-3, 6-4.

Thus, Nadal completed his round-robin undefeated, and he's in the semifinals for the fifth time. On two of those occasions, he moved on and lost in the final. He knows what he's up against, but this year the lack of great expectations might have taken off some pressure and enabled him to operate with a looser hand.

"Today I feel free," Nadal had proclaimed in his news conference after the best win of his year -- a straight-sets demolition of Andy Murray on Wednesday. "I feel [I'm] enjoying [myself] on court. ... I go day by day. Happy how the things are going the last couple of weeks."

Whether Nadal's feeling of liberation and one-day-at-a-time attitude will be enough to tide him through a struggle with Djokovic is the question of the moment.

Nadal's pal Federer smudged Djokovic's general aura of invincibility with that round-robin upset a few days ago. But top-ranked Djokovic has dominated everyone this year. He has won all three 2015 meetings with Nadal, without the loss of even a set. That includes a three-set whipping of the "King of Clay" in his own castle, Roland Garros.

But Djokovic isn't taking anything for granted. He has kept his eye on Nadal, knowing that the ironman with whom he's had such epic, ground-shaking clashes can't have shriveled up and died inside that 6-foot-1 frame of Nadal's. Djokovic told reporters the other day:

"You can feel [Nadal is] starting to get comfortable on the court," Djokovic observed. "The first couple of matches he played here, against [Stan] Wawrinka and Murray, showed that he feels more confident, shows that he's starting to miss less, serve efficiently, use his forehand much better."

Beating Djokovic under these indoor conditions is a tall order. Djokovic is vying for his fourth consecutive (and fifth overall) year-end title. It might be too tough an assignment for Nadal, who still didn't appear entirely like the Rafa of yore despite rallying to put the kibosh on Ferrer for the 24th time in 30 meetings.

Nadal served for the first set after breaking Ferrer for 6-5. The ensuing game was telling. Nadal played some tentative points to fall behind love-40, but played great to eliminate those three consecutive break points. Then he failed to convert a set point and struggled through two deuces -- only to get broken, which set up Ferrer to win a tiebreaker in which Nadal played miserably.

Sure, Ferrer can do that to people. But he's never been able to do it to people like Djokovic, Federer -- or Nadal 2.0.

Nadal hasn't played many emotionally or mentally grueling matches lately. His camp will have to worry about how much this bitterly fought win over Ferrer took out of him.

But fatigue is unlikely to be a factor, not with just two matches left in the tournament year, and so big a prize awaiting the winner. Nadal knows that he has put himself into a position to win all that, and write a truly spectacular surprise ending to the story of his 2015.

Unfortunately for Nadal, Djokovic -- plus Federer or another quality finalist -- will also play a part in writing that script.