How it happened: Thiem tops Zverev in four-set Australian Open semi

On Saturday, fifth-seeded Dominic Thiem reached his first Australian Open final, and third major final overall, with a 3-6, 6-4, 7-6 (3), 7-6 (4) victory over seventh-seeded Alexander Zverev. Here's how it happened.

Dominic Thiem:

Alexander Zverev:

While Zverev and Thiem are fairly evenly matched, I didn't think they were both playing at an equally high level at any point of this match—until this set. The rallies became quicker, but that didn't mean the quality of them was weaker. The offense, and subsequent counterpunching, exhibited from each player forced the other to go for bigger shots. Most of those shots landed in their intended targets.

Through 10 games, there were 10 holds—some more convincing than others. Neither man earned a single break point in this stretch, though Thiem climbed all the way back from down 40-0 in Zverev's 4-5 service game. Two points from defeat, Zverev stabilized in the nick of time.

Two more holds brought the set to a must-win tiebreaker for Zverev.

The pressure may have been too much for the first-time Slam semifinalist to bear. After a supreme serving display throughout the match, Zverev struck a double fault, while trailing 0-1, that wasn't close to catching the service box.

Thiem earned another mini-break for a 3-0 lead—before giving both mini-breaks back with errors: one on the backhand side, after the point appeared to be his, and another with his forehand.

Then it was Zverev's turn to blink, again. At 3-2, after a first serve, Zverev hit an awkward jumping overhead that nearly landed in the stands.

It was the final opening Thiem needed, before reaching his first Australian Open final. At 4-2, Thiem struck a 102-M.P.H. crosscourt forehand winner; he followed that with another crosscourt forehand winner—his 42nd winner of the match. (Both men had 42 winners at this point.)

He saved his 43rd for his second match point, at 6-4. It wasn't another crosscourt forehand winner, but it was set up by another crosscourt forehand bomb. Zverev got his racquet on the ball, but Thiem's net approach closed off the reply. The putaway couldn't have beem a softer shot, but for Thiem, it was the sweetest.

Thiem's superior power, coupled with Zverev's reticence to pull the trigger in rallies, had me thinking that the direction of the match was heading the Austrian's way, full steam ahead.

But great serving can mitigate an opponent's effectiveness on the ground—and function as all the offense a player needs. That was the case for Zverev, who, after holding for 5-4, had landed an incredible 31 of 32 first serves in play this set. Yet the German's most impressive service point, to that point, was the one where he needed to hit a second serve.

At 4-4, 30-30, and having used all of his challenges, Zverev was apoplectic when a first serve that appeared to be an ace—watching from thousands of miles away, I thought it caught the line—was called out.

It felt like the moment when Zverev would crack. What did he do? He hit a second-serve ace—followed by some choice words than earned him a code violation. (Replay would show that the first serve indeed landed out, by the slightest of margins.) On the very next point, Zverev hit a first-serve ace, no questions asked, that took him to 5-4.

Then, it was Thiem's time to answer the call in a problem spot. Twice, in fact, when he saved set points at 4-5 with searing winners: one a backhand down the line, another a curling forehand. Both left Zverev watching in admiration, much like the fans in the stands.

A tiebreak was needed to decide the set between two evenly matched players. Thiem began it with a gorgeous half-volley winner to earn a mini-break lead, then won the next two points on serve. Thiem's three-point advantage remained at 5-2—and at 6-3, after Zverev's serve, when the Austrian cracked a forehand down the line for another jaw-dropping winner.

Thiem closed out the set with another jaw-dropping winner, a flat crosscourt backhand that barely cleared the net and barely bounced off the ground.

For as good as Zverev's first serve was, he simply didn't enough of those points—and certainly not the biggest ones. Look at these numbers:

When Zverev double faulted twice early in this set, it was clear that we had moved past the "Sascha = Karlovic" portion of the proceedings. But a question remained: could Thiem, who in the first set looked nothing like the player that had just overcome Rafael Nadal, take advantage?

He did, but it wasn't without more struggle. Thiem was broken for the fourth time in the match at 2-3, and even though he quickly rebounded with a break back, he didn't handle prosperity well—until the very end.

Serving at 15-30, 5-4, Thiem found himself in the middle of a frantic volley exchange. His hands were good enough, though, to quickly answer Zverev's shots and find an opening, which denied the German two break points.

Still, Zverev would earn two break points in this game, one at 30-40 (off an overhead miss) and another after the first deuce, testing Thiem's mettle once again. Shots Thiem would normally put away were coming back, and the pressure seemed to be getting to him in the set's biggest moments.

But a winning a long rally to save Zverev's second break point of the game (and, as it turned out, final break point of the set) finally calmed Thiem down, and he served out an important game to level this semifinal.

A critical third set awaits both men.

As Zverev smacked an ace to consolidate his second break of serve, and lead 5-3, he had just landed his 18th first serve—out of 20 attempts. His confidence, shaken just weeks ago with a double-fault-ridden showing at the ATP Cup, has swung in the other direction and reached an all-time high. Zverev had famously never reached the semifinals of a Slam before this fortnight, but everything seems to be changing for the oft-maligned but unquestionably talented German.

It was so bad for Sascha earlier this month that Belinda Bencic suggested that, as part of the Australian bushfire relief effort, Zverev make a donation for each double fault he hit:

Zverev will make a donation to the cause, alright. Should he go on to defeat Thiem—who hit 13 unforced errors in a rather lethargic performance—and then win the title, he'll give his entire, 4,120,000 A$ prize to the cause.

"Of course, if I win the $4 million, it's a lot of money for me," he said. "I'm not Roger [Federer], I'm not LeBron James, something like that. This is still big.

"But at the same time I know that there's people right now in this country, in this beautiful country, that lost their homes and actually they need the money. They actually depend on it, building up their homes again, building up their houses again, building up the nature that Australia has, the animals as well.

"I think there's much better use for those people with that money than I have right now."

Safe to say that there are plenty of tennis fans, and Australians, rooting for Zverev to keep up whatever has gotten into him during the first set, and during the Australian Open.