MELBOURNE, Australia -- The biggest thing I'm impressed with, especially in a young player like Marcos Baghdatis, is his mental toughness.
Baghdatis came back from down two sets to love and then came back in the fifth set when he was down a break.
Then, when he was ready to serve for the match, the rain came.
After the rain, he got a bad line call from the umpire.
All that happened and Baghdatis didn't flinch.
Those are signs that tell me he's a player ready to take the next step.
I felt I played my best tennis when I was 25 or 26 years old, when mentally I was starting to mature and could handle certain situations. Physically, I was quick and strong, and I could recover after little injuries.
But there are special athletes who are able to do it in their teens. Pete Sampras won the U.S. Open at 19, Michael Chang won the French Open at 17, and Andre Agassi was knocking on the door as a teenager. These are special athletes who had not only the talent physically but also the mental toughness of a champion at such a young age. When those two worlds collide, there is a special individual.
Baghdatis is 20, but already we are seeing what he can do physically and how well he holds up mentally.
There wasn't a specific turning point in this match. He just stayed with the game plan.
The biggest flaw of clay court players such as Nalbandian, Guillermo Coria or Rafael Nadal is that they lack a knockout punch. They are grinders on the court, but they can play only so long when an opponent knows they don't have that one shot that can put him away.
Nalbandian doesn't hit a big serve and doesn't have a monster forehand winner that knocks opponents off the court.
Baghdatis does. He sets up the point, opens up areas and, boom, hits a winner. He changes gears and paces with his ground stroke and tempo. Nalbandian, by contrast, starts the same way and ends the same way, whether he's up or down. It's very predictable. The toughest thing for clay court players to do is to put their opponent away.
Nalbandian is a workhorse. Beating him after being down two sets to love in the semis of a Grand Slam is not a fluke.
Baghdatis has passed every test. If he plays Nicolas Kiefer, there's no doubt he has a chance. Even if he has to play Roger Federer, it's going to be a lot of fun to watch.
Former ATP Tour pro Luke Jensen is providing ESPN.com with analysis during the Australian Open. Jensen, a two-time All-American at USC, captured the 1993 French Open doubles crown with his brother Murphy.