might not even be a concern for sagan. he's stated a focus on monuments this year, so he and cav might have a few head to heads, at best. additionally, sagan has two green jerseys so far and one was secured through a team effort on a single stage. but, should the three come together at a race, i think sagan and kittle have the skills to latch on to cav's train.
He's a pretty special rider for sure. Talent to burnt and he makes it look easy.
The TDF Green jersey competition was a foregone result very early in the 2013 TDF.