Throughout his career, and especially on clay, Rafael Nadal has dominated his fellow Spaniards.  His route through the ATP 500 draw in Rio de Janeiro has featured three more such victories, but not all of them with equal ease.

Understandably rusty in his first match after a back injury, Nadal did just enough to avoid a third set against Daniel Gimeno-Traver in his opener.  Then, he demolished Albert Montanes as his confidence in his health started to return.  With that match and a quarterfinal rout of Joao Sousa behind him, he entered his semifinal against Pablo Andujar having lost only four games in his last four sets.

Nothing spectacular or unusual had leaped to the eye when watching Andujar, a standard clay specialist whose best result came in Madrid last spring.  A surprise semifinalist at that Masters 1000 tournament, Andujar could not seriously challenge Nadal there.  On the other hand, the 40th-ranked man had played two extremely tight sets against the world No. 1 at Roland Garros in 2011.  Although he lost in straight sets, Andujar established a precedent that day for his ability to test Nadal.

Even with that precedent in mind, however, few could have expected the underdog to blunt what looked like a runaway train.  And yet Andujar seemed to believe that he could, pouncing on an uncharacteristically erratic Nadal in the first set.  His confidence grew as the set progressed, and it became increasingly obvious that the 13-time major champion had left his best tennis somewhere else in Rio.  Pummeling an inside-out return for an insurance break, Andujar hung a stunning 6-2 set on the greatest clay player in history.

This was merely the signal for Nadal to dig into the red trenches.  Weathering an arduous service game early in the second set, he used the momentum shift of that escape to earn the only break that he needed.  To his credit, Andujar continued to battle through all of Nadal’s service games, which were more precarious than usual.  He also clung tenaciously to his own serve, keeping the pressure on the world No. 1 by staying within a single break.

When Nadal closed out the second set, therefore, he surely knew that the battle was not yet over.  During the early stages of the third set, an undeterred Andujar appeared to hold the upper hand.  He tried to disrupt Nadal’s rhythm by hitting behind him along the baseline and attempting to redirect his groundstrokes down the lines as often as he could.  These tactics led to plenty of wild unforced errors, but they also produced the depth and unpredictability that kept the favorite at bay. 

Nevertheless, Nadal fended off a cluster of early break points that could have handed the underdog an early lead.  His familiar grit surfaced during a seventh game in which he broke serve with two massive forehands after Andujar had led 40-15.  Surely that sequence marked the end for the spirited underdog, who already had recorded a top-20 upset this week over Fabio Fognini?

But Andujar had not abandoned the struggle.  Needing to break Nadal almost immediately, he achieved the task with another inside-out winner off his return of serve on break point.  A quick hold put the 13-time major champion’s back to the wall at 4-5 in the third set.  Andujar moved within two points of victory, relentlessly tracking down more Nadal rockets than one could have imagined.  Well-placed serves allowed the world No. 1 to dodge that bullet.

Each man held serve uneventfully to reach the first final-set tiebreak that Nadal had played on clay since 2009.  He had won all three of the final-set tiebreaks on his favorite surface, including thrillers against Novak Djokovic in Madrid and Roger Federer in Rome.  Despite struggling to break each other’s serve throughout the last two sets, the Spaniards started the tiebreak with five straight mini-breaks.  Nadal became the first man to win a point on his serve just before they changed ends at 4-2, but he surrendered the advantage immediately. 

At that stage, the quality of tennis soared from compelling to breathtaking.  Each man forced the other to hit four or five outstanding shots to win points, yet neither man gave an inch on his serve.  Andujar’s delicate touch at the net stymied Nadal more than once, while the world No. 1 also froze the underdog more than once with sharply angled passing shots.  Nadal saved a match point at 5-6 and another at 7-8, the first by drawing an Andujar backhand error and the second with a service winner.  Andujar showed just as much courage in erasing match points against him with fearless shot-making

The turning point came at 10-10 in the tiebreak, when Andujar’s nerve betrayed him for the first time.  On the first stroke of the rally, he dumped a passive backhand slice into the net for the decisive minibreak.  Nadal found himself on the defensive again on the next point, but he retrieved just enough forehand blasts to keep the rally alive until one last Andujar error. 

After a match that lasted nearly three hours, filled with protracted and punishing exchanges, the world No. 1 must regroup quickly for the Rio final against Alexandr Dolgopolov.  This quirky opponent already has defeated two notable Spaniards this week in Nicolas Almagro and David Ferrer.  Nadal will enter as the heavy favorite once again, but today showed that nothing in Rio should be taken for granted.