It goes without saying that it would have been a horrible result if Roger had lost to Tommy Haas however in watching his play, Roger didn't necessarily beat Tommy, it's one more example where learning how to close the door is as important as learning how to hit a forehand. When you're in the lead, it very hard to stay in the lead.
The mindset is after winning the 1st Set, that you can now relax a bit. As a professional Player, you would think by now they would & should know that matches change in the blink of an eye but still you see time after time where the person that won the 1st Set loses the Match.
Well what happens is simple. the person that lost the 1st Set is now going to become extremely dangerous given they now have nothing to lose other than a match. They will immediately analyze their play and make the necessary corrections whereas the person that won feels all they have to do is stay the course. Why would you stay the course if your opponent has changed their tactics?