Rafael Nadal came into the fourth round having not dropped a set so far in the Australian Open. His fourth round opponent was not going be a pushover in Diego Schwartzman. The Argentine stands at just 5'7'' but does indeed pack a punch and can grind his way through a match.

It wasn't easy for the Spaniard, but he found a way through to win 6-3, 6-7(4), 6-3, 6-3. He will now face Marin Cilic for a spot in the semifinals. With his win over Schwartzman, Nadal has guaranteed himself to finish the tournament as world number one.

Nadal Overcomes Testy Service Games To Take Set

Despite the scoreline in the middle of the first set being three-all, Nadal was being tested in his service games early on. His first real troubles came in the seventh game of the set after a missed volley and a forehand error put him triple break point down. Schwartzman had good looks on a couple of chances but two loose forehands long, along with a Nadal winner brought it back to deuce. The Spaniard was able to hold for 4-3 and was hoping to make some in roads on the Argentine's serve.

Nadal found himself up double break point after a forehand down the line was called out but was good upon the challenge. The Spaniard was a bit impatient in his patterns though, giving back his break chances. He'd convert later on though, after the Argentine hit a shot into the net, giving Nadal a chance to serve out for the set.

A hold at love was just what Nadal needed to close out the set 6-3. 

Nadal finds a way to take the first set (Michael Dodge/Getty Images)
Nadal finds a way to take the first set (Michael Dodge/Getty Images)

Schwartzman Claims The Breaker

Nadal found himself with more confidence after that late break in the opener and broke to start the second set. With a set and a break lead in his hand, Nadal was looking to get even more aggressive. However, Schwartzman was able to get the break right back for one-all. 

The break gave Schwartzman a new confidence as he looked to be the aggressor more often, but the 24th seed was broken in the fifth game after his volley attempt on Nadal's backhand pass went wide. 

The 24 seed had two break chances for four-all in the second and would convert to level the set. A backhand error a few games later though gave the Spaniard a chance to serve for a two sets to love lead. Some timely hitting from the Argentine had Nadal on the defensive and a forehand winner brought the second to a tiebreak.

Pinned in the corner, Schwartzman pulled out a forehand winner down the line to set himself up with the first mini-break lead of the tiebreak. An errant backhand gave Schwartzman the set, much to the delight of the crowd who wanted to continue seeing a fantastic match.

Schwartzman really tested Nadal (Michael Dodge/Getty Images)
Schwartzman really tested Nadal (Michael Dodge/Getty Images)

Nadal Grinds To Victory

The second set was grueling, going 80 minutes long. Both players were hoping to strike early in the third set to keep it much shorter this time around. A double net cord gave Schwartzman just that chance but was unable to convert. Nadal's opening service game went quite awhile but was able to hold and then find a break just a few games later to give himself a 3-1 lead. An ace helped the world number one close out the set 6-3.

Over three hours into the match, Nadal saved five break points just to get to one-all. The missed opportunities came back to bite Schwartzman, being broken in the next game. The world number one went on to save a couple more break points and held for 5-3 as he was just one game away from closing out the match.

Third time was indeed the charm for Nadal as his backhand return winner right to the corner gave Schwartzman no chance to get a ball back into play as the world number one gutted out a victory in nearly four hours. The two shared a warm embrace at the net as Nadal applauded Schwartzman for his efforts.

Schwartzman and Nadal share a hug at the net (Michael Dodge/Getty Images)
Schwartzman and Nadal share a hug at the net (Michael Dodge/Getty Images)