One fourth round matches pits two 30+ players against one another: Florian Mayer (Germany) vs. David Ferrer (3rd seed, Spain). Ferrer is a regular in the late stages of Majors, having made at least the quarterfinals of all four multiple times. He is one of the most respected players on tour and is the easy choice as best active player never to have won a Slam.
For Mayer, making it this far is a much bigger deal. When healthy, he has been a solid top 100 player. However, this is only the third time in his career that he has made it past the third round of a Major and the first time he's done it at a tournament other than Wimbledon. Ferrer's a tall order for any player but Mayer may have a shot. His head-to-head record against the scrappy Spaniard is a respectable 3-4, including a hard court win this past fall in Shanghai.