Safety car.

Though Lewis overall is the better driver, that sums up how he made his move at this race. Bottas pitted first, and the undercut was working. He was putting a bigger gap on Lewis in his out laps. Lewis had the time advantage of pitting under the safety car, the easy laps on the new tires due to the safety car that let him run the tires even deeper, and the advantage that everyone had cool tires on the restart.

The fast lap was brilliant considering the tire age. But it's been confirmed that Bottas had the disadvantage of the battery issue, as well as having made his fast lap attempt when still heavier on fuel.

So overall, I'd say if anything Bottas stepped up to the level of Hamilton this race. It's one of the few times they went wheel to wheel on track and Lewis didn't come out on top. Lewis drove his usual great race, but luck played a large part in the win IMO.