They sure as hell didn't look tired last night.
As for the rest of the squad, it's also strong. Not as strong as the starters but that's the same for every side. When you have players who are in no way guaranteed starters like Kranjcar, Pienaar, Pav, Defoe, and Sandro available to come in and do a good job, you're going to do well. Livermore came in yesterday and was outstanding. As Cronky has said, their defence looks as solid as it has been for a long time.
Spurs are the real deal. They won't win the thing this year but they are firmly establishing themselves as a serious top 4 (I'd argue top 3) team.