Wondering what the Tournament of Champions is, and how we got here? Read more about our 50th Anniversary Celebration and get caught up on all the matches so far.

“A great match-up,” Tim Mayotte says. A battle of baseline “beasts,” Leif Shiras agrees. Nadal and Agassi were the premier hitters of their generations, and they would have had a titanic rivalry if they had been the same age. But by the time they faced off in reality, in 2005 and 2006, Agassi was 35 and nearing retirement; it was Nadal who knocked him out of Wimbledon for the last time.

Each man won with his forehand and backhand rather than his serve, and each was successful on all surfaces—Agassi and Nadal are two of just four men in the Open era to complete career Grand Slams. A match between them would have been decided by who could assert his will, in his own way, from the backcourt. Could Nadal push Agassi back with his topspin? Or would Andre take those balls on the rise and rush Rafa?

Nadal’s speed and defense may have been the difference. “Despite being an efficient and balanced mover,” Mayotte says, “Agassi was not a fast one. Nadal’s angles would drive Andre off the court.” Still, while Nadal would be favored on clay, Agassi was every bit his match on his own natural surface, hard courts. A final tug of war on grass would have been a sight for tennis fans to see. As for the result, Brad Gilbert, Agassi’s old coach, admits that he has it going to the stubborn Spaniard. “Nadal begrudgingly toughs out Andre,” Gilbert says.

Quarterfinal: (2) Rafael Nadal vs. (10) Andre Agassi

Quarterfinal: (2) Rafael Nadal vs. (10) Andre Agassi