Adorable Video -- My Dog Saved Baby Dolphin ... Man Says (video)

Lassie ain't got nothin' on a new 4-legged hero named Leila -- who saved a baby dolphin that beached itself in the UK earlier this month ... and it was all caught on video.

Leila's owner posted the footage online -- showing the heroic canine tending to a tiny dolphin that was stuck on some rocks last weekend at Criccieth Beach in Wales .

Turns out, man's best friend became dolphin's BFF that day -- because Leila alerted her human, who was able to push the little guy off the rocks ... and it successfully swam away!