Is Ana Ivanovic still a threat?

MELBOURNE, Australia -- What exactly is Ana Ivanovic's standing in tennis?

Is Ivanovic destined to win another Grand Slam title, or will the glamorous Serb, whose popularity currently outweighs her results, linger as part of the tour's second tier, a player capable of pulling off upsets here and there but not a contender at majors?

"I think she's still a Grand Slam threat," said Roger Rasheed, an analyst with host broadcaster Channel 7 and the former coach of Lleyton Hewitt. "Looks like her game is getting more structured now, she's gaining more confidence. She just needs some time now. She's still young, very athletic and has the tools."

We saw her vast tools in 2008, when Ivanovic, who plays Petra Kvitova in a round-of-16 clash in Melbourne on Monday, won the French Open and rose to No. 1 in the world.

She was what the women's tour wanted: attractive, well-spoken and talented.

But a wrist injury and serving issues sent her ranking -- and confidence -- tumbling. Ivanovic's propensity to overthink hurt her as well, something she has admitted.

Since ending 2008 at No. 5, she's never finished a campaign inside the top 20. Nor has she landed in a Grand Slam quarterfinal since her historic run at Roland Garros four years ago.

Ivanovic, 24, is one victory away from snapping the skid. She's thinking further ahead than that, too.

"I really hope I can go far and spend another week here," Ivanovic said. "That would be fun to compete next Saturday [in the women's final]."

Ivanovic maintains things are going well with newish coach Nigel Sears, although that's not saying much. Ivanovic habitually changes coaches and fitness trainers. Ivanovic says she stepped up her fitness work in the offseason, crediting Sears.

She also enjoys competing in Australia, given family ties. Her boyfriend, Aussie Adam Scott, has been with her in Melbourne throughout the tournament.

Ivanovic, who was slightly ill during her third-round victory against American Vania King, will need everything working against the second seed and one of the tournament favorites, Kvitova.

Although Ivanovic is 3-0 against the Czech lefty, all three wins came in 2009 or earlier, when they were different players.

"Petra is definitely playing some great tennis," Ivanovic said. "She's one of the hottest players at the moment. It's going to be a great challenge for me."

For now, too much of a challenge, according to Rasheed.

"Ana's got some game," Rasheed said. "But at the moment she plays these really good patches and then just has a few moments. Until that's shored up and worked through, it'll be tough."

Prediction: Kvitova in two.

Novak Djokovic (1) versus Lleyton Hewitt

After perusing the Australian Open draw last week, local tennis fans would probably have taken one Aussie man in the fourth round. Given Hewitt's injury woes, 19-year-old upstart Bernard Tomic had to be the likeliest candidate.

Tomic made it.

Guess what? Hewitt has given him company.

Hewitt benefited from Andy Roddick's retirement in the second round, but luck had nothing to do with upsetting Canadian Milos Raonic in four sets Saturday night.

"I don't think a lot of people would have given me a lot of hope when the draw came out to be in the fourth round," Hewitt, 30, admitted in a news conference. "I've laid it all out on the line."

Would anyone expect anything less from the so-called "little Aussie battler?"

Hewitt was unusually emotional after defeating Raonic, crumpling to the ground as if he'd reached a Grand Slam final.

"It's pleasing to come through like I have the last three matches," Hewitt said. "I think in terms of how much pain and stuff I played with last year, it's really only my team and people close to me and probably the Davis Cup boys who sort of know what I've had to deal with."

Although Tomic's confrontation with Roger Federer on Sunday night had all of Australia captivated, Hewitt's clash with Djokovic is nearly as intriguing. It's a two-time Grand Slam winner and former No. 1 against the current No. 1 and four-time major winner.

Despite winning four in a row against Hewitt -- three in Grand Slams, including the 2008 Australian Open -- Djokovic knows Hewitt won't be overawed.

Hewitt is Djokovic's first significant test this tournament.

"Lleyton has been playing some really good tennis," Djokovic said in a news conference. "I think the best that we have seen him play in the last two years."

If Djokovic is on his game, Hewitt will have to roll back the years even further.

Prediction: Djokovic in three.

Maria Sharapova (4) versus Sabine Lisicki (14)

Lisicki, the German with one of the most lethal serves in the women's game, practiced with Aussie Samantha Stosur in December.

Stosur never plays well in Australia, but thankfully for Lisicki, that didn't rub off on her.

Even entering the Australian Open with a questionable back -- the latest in a catalogue of health woes -- Lisicki advanced to the fourth round by rallying against two-time Grand Slam winner Svetlana Kuznetsova.

Lisicki has tangled with Sharapova (who owns one more major than Kuznetsova) before on the big stage, at Wimbledon in 2011, and lost in straight sets.

"I'll have to be better this time," she said. "I'll go in and fight for every point."

Sharapova has bulldozed her first three opponents, dropping five games total.

Prediction: Sharapova in three.

London-based Ravi Ubha covers soccer and tennis for ESPN.com. You can follow him on Twitter.