From veterans to teenagers, power to finesse, funny to feisty, there's a pleasing variety of playing styles and personalities with a lot to offer.
One is a surprise, the other is not, and the contrasts don't stop there. Bouchard, the surprise who emerged from the quarter vacated by Serena Williams, is the 2012 Wimbledon junior champ and a teenager who plays older than her years. Li is over 30 and the 2011 French Open champ yet is trying to improve like a player just starting out.
Bouchard is a counterpuncher, a good mover who absorbs pace and redirects the ball to keep opponents off balance and create openings.
"I think I just really try to take the ball early," she said. "I think that's good because it takes away time from the opponent. She has less time to guess where I'm going or try to read where I'm going. I think that's an advantage I try to use on the court."
As she showed in coming from a set down to defeat Ana Ivanovic in the quarterfinals, the 19-year-old Canadian is a natural on the big stage. She began to really harness her game after the US Open last year, significantly improving her performance and results. But she lacks a big weapon and can be vulnerable against big hitters.
Li, on the other hand, is a puncher -- a power player who is trying to develop her serve-and-volley with coach Carlos Rodriguez, who worked with retired former No. 1 Justine Henin. Though she can hit almost anyone off the court when playing well, nerves can get the best of her.
Their personalities are equally different. The glamorous Bouchard, who admires Maria Sharapova, not only wears the Russian's clothing line but shares her inclination not to get close to other players.
One exception is the fun-loving Laura Robson, a good friend from juniors -- two years ago, the two produced an entertaining music video featuring various players showing off the latest dance moves. The Australian crowds, including the boisterous, chanting "Genie's Army," have been impressed -- or at least they were until Bouchard was asked in her last on-court interview who she would like to date.
There were boos as she replied, "Justin Bieber."
Li's on-court interviews are typically big hits, starting from her run to the final in 2011 and all the comedic performances about her husband that accompanied it. After reaching two finals at this event, the popular Li can expect the crowd to lean her way in Thursday's match. The contest will also likely be decided by her winners and errors.
Bouchard is not expected to beat herself, so Li will need to manage the pressure of being the favorite and take effective control of the points. Bouchard, who will be playing her first Grand Slam semifinal, is aware of the gap in experience with Li but isn't conceding any advantage.
"Obviously, a lot of the players now are playing better with age. So for sure she's still at the top of her game and it will be tough. For sure she's been in a lot more situations like this than me," she said. "I think I've been doing well this week handling big moments on court. So I'm feeling confident and just excited to play."
The contrast in this match is in playing styles.
Reflecting her nickname, Cibulkova produces plenty of power with her undersized but muscular frame yet remains speedy enough to chase down her opponent's shots. Radwanska is known for her creative shot-making, compensating for her lack of consistent power with improvisation, anticipation and variation.
That was on full display during her three-set win over Victoria Azarenka in the quarterfinals, as she wowed the crowds with some stunning winners. Other than that, the two are almost the same age and came up through the juniors together.
"I think it's always tricky to play someone that you know for so long, play so many times, as well," said Radwanska. "Every match is a different story, especially when it's a semifinal of a Grand Slam."
Radwanska has been the more successful of the two, reaching a Grand Slam final at Wimbledon and getting as high as No. 3 in the rankings. She also leads the head-to-head 4-1, but the last two matches reflect how much Cibulkova's form can vary -- she lost 6-0, 6-0 in their match at Sydney at the beginning of last year, then won in three sets when they next met at Stanford.
But the Slovakian has been working on playing a more balanced, consistent game, rather than the all-out aggressiveness she was trying a few years ago. Either way, Radwanska remains the heavy favorite. Cibulkova will need to stay aggressive, find plenty winners and pounce on her opponent's weak second delivery to avoid getting outmaneuvered in Thursday's match.
After upsetting Maria Sharapova in the fourth round and following up with a strong quarterfinal performance, she's prepared for the challenge.
"If you play against the best players, you cannot do the same things all the time," said Cibulkova. "You have to change sometimes the tactic. When you go for the winner, I cannot go into the same spot, you know."