French Open 2013: Most Compelling Matches Set for Day 9 at Roland Garros

Many of the world's best players will compete on Day 9 of the 2013 French Open as the field continues to shrink.

Some of the quarterfinalists have already been decided on the men's and women's side. Many of the lower seeds have been pruned away, leaving only the best of the best to compete for the chance to win this year's championship.

Heading into Monday's action, these are the matches that have a chance to develop into instant classics. The winners will move on to the quarterfinals, while the losers will lick their wounds and prepare for the next tournament.

Novak Djokovic (No. 1) vs. Philipp Kohlschreiber (No. 16)

Djokovic hasn't lost a set thus far in the 2013 French Open, but he'll surely be tested by Kohlschreiber on Monday in their fourth-round match.

The two have competed three times before, with Djokovic winning two of the matches. The lone win for Kohlschreiber, however, came in 2009 in the third round of the French Open. Kohlschreiber easily won that match in straight sets, as noted by tennis enthusiast Farhan Shah:

Both players have had an easy time of it the past couple of rounds.

Kohlschreiber toughed out a four-set victory in the opening round, but he won by way of walkover in Round 2 and won in straight sets in Round 3. 

Djokovic had an early test as well in Round 1, but he has been seemingly on autopilot throughout the tournament so far and is playing exceptionally well right now. 

Maria Sharapova (No. 2) vs. Sloane Stephens (No. 17)

Like Djokovic, Sharapova has been able to cruise through the first few rounds at Roland Garros without hardly breaking a sweat. She'll be tested in Round 4 against Stephens, who has also been playing well at the French Open. 

Stephens didn't fare well against Sharapova the last time they met, however, losing in straight sets to the world's No. 2 player at the Rome Masters. 

That said, this will be Sharapova's first real test of this year's French Open. She's faced nothing but cupcake opponents to this point in the proceedings, and Stephens has a better overall game than her earlier contestants.

Should Stephens win this match, not only would it be a tremendous upset, but it would also be a continuation of what's already been a compelling story: American women performing better than expected.

Rafael Nadal (No. 3) vs. Kei Nishikori (No. 13)

Besides the fact that Nadal will be playing (he's always a compelling draw at Roland Garros), this match has added appeal. Nishikori is the first Japanese man to make it into Round 4 since 1938, according to BBC Sport, though he was unaware of his accomplishment:

Nadal hasn't looked quite like himself in the early rounds of this year's French Open. He's been pushed to four sets twice, and it has taken him a bit of time to get into the flow of his matches. 

Meanwhile, Nishikori is coming off an easy win against Benoit Paire in Round 3, and he is in prime position to pull off an upset.

He beat Roger Federer earlier this year at the Madrid Masters, he's playing well right now, and he has played Nadal tough in their only previous match. Although he lost in straight sets to the King of Clay, Nishikori earned seven break-point attempts and actually had an early lead on Nadal in the first set.

Should Nadal come out flat again as he has in his early matches at Roland Garros, Nishikori could shock the tennis world with the biggest victory of his young career to move on to the quarterfinals.

Follow me on Twitter @JesseReed78