be in the groove

1. To be immersed in a particular task and thus working smoothly and efficiently. Now that I'm in the groove, I think I'll be able to finish this paper tonight—ahead of schedule! If I'm in the groove, I can clean for hours. Sorry, what do you need? I was in a groove filing this paperwork.

2. To experience a particularly successful period. Three championship titles in a row? Wow, that team is really in the groove. That company is totally in a groove—every device they release practically flies out of stores. He's an ace starting pitcher, and once guys like him are in a groove, good luck knocking them out before the seventh inning.