Collin McHugh versus Yordano Ventura.
By virtue of the Wild Card Game, the Astros didn't get to set their rotation the way they wanted to. The Royals did, and they played the hot hand, with Yordano Ventura taking the ball for an important G1 of the ALDS. Collin McHugh ain't no slouch on the hill, however, and he seems like a tough cookie in terms of his mental will and endurance. Not the worst guy to have start a series.
The Astros have been playing elimination baseball for a while now. G162 was an elimination game of sorts - really, the whole of the last two series' were - not to mention the Wild Card Game.