Dog vs Kitten

We just got a new kitten, she's maybe 2 months old. Very sweet. Very curious.

Combine that with my 4 year old border-collie mix that we adopted two years ago. He's a very sweet boy too, doesn't have a mean bone in his body. He is, however, extremely excited about the new kitten.

I'm trying to let the kitten explore the house but he is right on her, his nose basically attached to her at every step. To her credit she doesn't seem scared of him, but he's got about 30 pounds on her and tons of energy.

If he sees the kitten across the house he'll run straight at her and stick his nose right on her butt…except he's kind of clumsy and I don't trust hit to not accidentally trample the kitten.

If the kitten doesn't seem too bothered should I just let the two of them do their thing?Or should I put my boy outside / in the other room until she kind of gets her bearings?

Kitten does have a bathroom in the house that's hers with beds and her litter box where she can escape if needed.

Also to add to the mix we have a 12 year old cat that seems not at all interested in the new kitten at all (older cat and dog get along fine too.) Sometimes the older cat and dog will play chase but the cat can just jump onto the couch to escape…kitten doesn't have those hops yet.