Your right, how just I could forgot that Roger was alone all time, oh wait...
So we get at the very minimum Roger whole crew vs Rocks, and there is big possibility for Marines(not Garp only) faced Rocks in the battle to protect Celestial Dragons, which was already confirmed in this page:
, so there wasn't Garp and Roger solo Rocks.
Well, in anime we saw how they take Shanks, they said guard leave, wasn't feared of him, saying more thay say something that he wasn't suppouse to come there. That was exactly Eye-to-Eye Meeting.