I don't think Rafa should concentrate on the #1 ranking. Rankings and stats are fine, but to me they're secondary to a player's entire career. Plus, you can't win everything, so you have to accept what is a very exciting and prosperous career.
Sometimes as fans we want more for our player than is humanly possible, but I just want to support Rafa as long as he plays. If he quits tomorrow I will be eternally grateful for the high caliber matches I've been able to enjoy.