Lopsided

It’s a Tic-Tac-Toe of quads, but I ran out of digits when placing the quads, so it’s a bit top-heavy and somewhat right-heavy, too. That’s okay, though. There are more than enough digits to solve the puzzle, and it’s not too ugly, right?

Right?

Rules:
Normal Sudoku rules apply.
Digits within circles appear at least once in cells touching the circle.

Estimated difficulty: 1 out of 5