Federer became #1 at 31.
If he was 25 now, he would be winning and dominating all the slams except for the FO.
It wasn't until Federer was almost 27 that he lost to Nadal at other slams besides the FO and to Djokovic at a slam.
At almost 32 he still hasn't lost to Murray at a slam. Might change this year but the Swiss is pushing 32...