No two tennis shots are ever the same, and the same can be said for matches.
There are countless factors at play, mainly the time of day, the stage and the surface. But for the dark-horse contenders, who are often up against overwhelming competition, the key is to make the most of those factors and capitalize on the opponent's weakness.
For three dark-horse singles contenders set to take the court on Day 9 in Melbourne, the keys to victory are simple to understand, but another story altogether when it comes to execution.
Let's take a look.
Ekaterina Makarova Must Be Aggressive, Go for Broke
Women's No. 19 seed Ekaterina Makarova will take on countrywoman Maria Sharapova in the quarters on Day 9, and will need to be super aggressive and unrelenting in order to somehow pull off the upset.
Makarova has already disposed of No. 11 Marion Bartoli and No. 5 Angelique Kerber, but in order to take down the No. 2-seeded Sharapova, she's going to need a performance similar to her third-round win over Bartoli, in which she recorded a ridiculous 51 winners.
Sadly, though, 50-plus winners may not even be enough to top the 2008 Aussie Open champ on Tuesday.
Makarova must set the tone from the opening serve of this match. Sharapova is on fire right now, and as they say, seeing the ball as if it were the size of a basketball. Makarova will need to be special once again, this time playing a fearless game, often going for winners and looking to shorten points at the net in order to catch her fellow Russian off guard.
Tomas Berdych Must Find Early Success, Win Quickly
Czech star Tomas Berdych has never been beyond the quarters of the Australian Open. The biggest key for him to change that in 2013 will be to find early success against top-seeded Novak Djokovic on Day 9, and to win games and sets quickly.
After all, Berdych hasn't dropped a single set at Melbourne Park this January.
In the Round of 16, Stanislas Wawrinka jumped up on Djokovic in a hurry, winning the first set 6-1. But even that wasn't enough, as the Serbian came storming back, winning three of the next four sets to advance to the quarters. Despite falling in the end, Wawrinka threw down the best game plan for upsetting Djokovic.
The key is to jump on him early and put him in a bit of a hole. Not that Djokovic panics when he's trailing, but as is the case with anyone, you begin to press when you're behind. If Berdych can force Djokovic into a pressurized situation early on, he is more than capable of springing the upset and making his way to the semis at Australia for the first time in his career.
Li Na Must Avoid Mistakes, Force Her Opponent to Beat Her
Though it sounds obvious and can be considered a key for every player, avoiding unforced errors will be hands-down the most important key for 30-year-old Li Na the rest of the way in Australia.
Li has been reducing her unforced error count in every match since the first-round, and that bodes extremely well for her in her upcoming quarterfinal showdown with No. 4 Agnieszka Radwanska on Day 9. When players avoid silly mistakes like double faults or sending forehands and backhands into the net, they force their opponents to beat them with winners or brilliant shots.
Plus, Radwanska has yet to record at least 20 winners in a single one of her early-round matches in Australia.
First-serve success and capitalizing on break-point chances will always be vital to any player's success, but in Li's case, avoiding the silly, costly errors will be the biggest key for her to upend Radwanska and forge a spot in the semis.
Follow Bleacher Report Featured Columnist Patrick Clarke on Twitter throughout the 2013 Australian Open for more reaction and analysis on the year's first Grand Slam.