Australian Open 2012 Scores: 3 Eye-Popping Results from Jan. 19

Two rounds of the Australian Open are in the books, and the tournament has had its fair share of surprises. Thursday's play was no different, with several results that probably caused tennis fans around the globe to make sure they read them correctly.

Here are three matches in particular with shocking outcomes from Day 4.

Lleyton Hewitt defeats Andy Roddick

Andy Roddick has been able to navigate most of his career without having to deal with many injuries, but it appears that all of those matches are finally catching up with the American star. He was forced to retire from his match with Lleyton Hewitt while trailing after three sets.

When Roddick isn't even able to make some noise in a hard-court tournament, it's a signal that the end is near. His serve isn't the dominant force it once was, as evidenced by just nine aces against Hewitt, and the rest of his game isn't strong enough to make up the difference.

Hewitt, on the other hand, looked rejuvenated as he cracked winners off both wings, giving his Aussie fans something to cheer about. Milos Raonic will be a terrific test to see if Hewitt's truly back.

Vania King defeats Anastasia Pavlyuchenkova

Roddick might be out, but Vania King gave American tennis fans something to cheer about by upsetting Anastasia Pavlyuchenkova. King is best known for her success in doubles (two major titles), but has come a long way as a singles player in recent years.

Her win on Thursday was more about an awful performance from Pavlyuchenkova, though. The rising Russian star had an astounding 61 unforced errors, which pretty much handed the match to King, and she took full advantage.

An appearance in the third round matches the best singles result in a Grand Slam event for King, who faces the always unpredictable Ana Ivanovic in her next match.

Julien Benneteau defeats Gilles Simon

In a battle of Frenchman, the underdog came out on top. Julien Benneteau almost blew a two-set lead, but he was able to regain his composure to advance in five sets. It's a massive disappointment for Simon, who continues to struggle in majors despite his high ranking.

You have to give a ton of credit to Benneteau. He went shot for shot with Simon for more than four hours and showed good fitness in the fifth set. It's a performance that solidifies him as a sleeper assuming he's not out of gas after the marathon match.

The bigger takeaway will be Simon's struggles, though. It's not a question of talent, as that's certainly there, but until he starts showing up on the biggest stages, his career results won't match his potential.