Istomin overall the better player, with better aggression and better tactics here. Mayer was struggling to find that aggression he usually has, although I am not sure how he played in the past rounds to know what his tactics were. Mayer served well though and kept him out of some tough spots -- he's quite clutch here in general. However, he had difficulty returning the Istomin serve, but when given the chance to break Istomin (had 15-40 opportunities during the 2nd Set) he wasn't able to break him due to Istomin's serving or a bit of tentativeness from Mayer plus Istomin keeping control of the ball. Oddly, Istomin was playing better in the 2nd Set, but Mayer had so many BP opportunities while Mayer didn't have much vulnerability on serve, and eventually Mayer did win the 2nd Set. 3rd Set was quite tighter with Istomin seemingly better on service games to not give much opening. Mayer also saved MPs on the 2nd Set, where eventually had snatched the 2nd. However he wasn't able to duplicate it in the 3rd Set where while he came back in the TB (and had an MP on his return but was saved by a corner Istomin serve) Istomin did well to convert his 2nd MP in the 3rd Set.