[MENTION=10606]LondonElite[/MENTION] laid it out pretty clearly.

A much safer way is flying into LAS the night before. (and not on the last possible flight of the night) You want to not really care about flight delays, and you want alternative flight options in case yours is cancelled.

You generally have to be borderline crazy to risk no-showing a long-haul flight because you tried to squeeze in a separate ticket positioning flight with little margin for error. But some people do it, and get away with it. Others would get a nice long vacation in LAS instead of Malaysia...