His side was trailing 2-0 in Turin, then his double got it to 2-2 and Alessandro Del Piero thought he'd won it.
However, Lech striker Rudnevs completed his hat-trick at the 92nd minute for a Europa League shock.
"It's a shame about that goal at the end, but none of us could really do much about that one," said Chiellini.
"Am I satisfied with my two goals? Compared to the result that's not even the second most important thing tonight, but the third."