Andy Murray shows his "big heart" in improbable, five-hour-and-45-minute comeback win

WATCH: The match point of Murray's marathon win in Melbourne

At 4:15 on Friday morning in Melbourne, after Andy Murray had put the finishing touches on his highly improbable, five-set, five-hour-and-45-minute comeback win over Thanasi Kokkinakis, he was asked the obvious question:

How in God’s name did you do that?

Murray started to talk about the usual things: How well Kokkinakis served, how the match had its ups and downs, how he played better as it went on, etc. Then he stopped and cut to the chase:

“And I have a big heart,” Murray said.

You can add those six words to anything else you might want to say about Murray’s game on this night.

He hit his forehand as cleanly as he ever has—and he has a big heart.

He constructed the rallies brilliantly at all the most important moments—and he has a big heart.

He was 43 of 51 at the net—and he has a big heart.

He forced his nervous opponent to hit as many shots as possible in pressure situations—and he has a big heart.

But even a heart like Murray’s needs to be give a chance to beat. And even a comeback artist of his renown needs to have the door to that comeback left ajar for a few seconds. Kokkinakis, who had never made it past the second round at his home Slam, obliged.

The opening came at the last possible moment, with Kokkinakis serving for the match at 5-3 in the third set. The Aussie had weathered a few runs of Murray brilliance, as well as his own meltdown over a time warning. Each time, though, Kokkinakis had reestablished control with his towering serve and forehand. Even in cool evening weather, with a slow ball, he fired 102 winners over the course of the match, 33 more than Murray.

The only problem was that when it came to firing the final winner, he couldn’t pull the trigger.

At 5-3, 30-30, Kokkinakis missed a routine forehand long, which gave Murray a break point. It was just one shot, but Murray wasted no time taking advantage of it; he broke with a forehand winner on the next point.

Fifteen minutes later, the same chain of events played out. At 4-4 in the third-set tiebreaker, Kokkinakis against missed a forehand long, and again Murray took advantage by cracking a service winner to reach set point

Finally, at 5-6, Kokkinakis cracked. Set up with the easiest of forehand volleys, he sent it—flubbed it, stoned it, sailed, muffed it, whatever awful word you want to use—five feet wide.

As ugly as that volley as, it was also illuminating: It seemed clear that Kokkinakis wasn’t ready to win this match. Two sets and two hours later, that fact hadn’t changed.

First, though, Kokkinakis did well to settle back down. He traded holds with Murray through the fifth set, and once again, with Murray serving at 4-5, put himself two points from victory. But once again, that was as far Kokkinakis got.

Up 15-30, he couldn’t pull the trigger. He missed one forehand wide, and another long, and Murray escaped with a hold. From there, Kokkinakis seemed to tire just a little, while the 35-year-old marched on. Murray hit a perfectly measured inside-out forehand winner to break for 6-5, and rifled one last backhand winner to hold for the 4-6, 6-7 (4), 7-6 (5), 6-3, 7-5 victory.

“There was frustration in there. There was tension. There was excitement, all of that,” Murray said.

Kokkinakis, who had never won a match of this magnitude, hit more aces and winners, and was in control for long stretches. But he couldn’t hit the winner he needed. Murray, who has been winning matches of this magnitude for nearly 20 years, had exactly as many winning shots as he needed, and not one more.

And did I mention he has a big heart?

The victory was the longest of Murray’s career, and it finished five minutes short of the Australian Open record, set by Rafael Nadal and Novak Djokovic in 2012.

“At the end, it’s obviously amazing to win the match,” Murray said in his 5 A.M press conference. “But I also want to go to bed now. It’s great, great. But I want to sleep.”