lucky break
A very fortunate or beneficial chance or happenstance. We were stuck in our investigation, but we had a lucky break when an anonymous source tipped us off to a possible culprit. "Hmph, lucky break," grumbled Mike, after his little sister got a hole-in-one on the very first hole of the course.
lucky break
and a nice break; a big breaksignificant good fortune or opportunity. I need a lucky break about now. She's never had a lucky break. Mary is going to get a big break soon.