Serena has won 18 of their 21 meetings. Their most recent match was in June 2015 on grass, Serena won in 3 sets. All 3 of their matches last year went to a deciding set.
Serena has not dropped a set so far. Radwanska pushed her the closest and took her to a second set tie break but won just 1 point in that tie break.
Stosur and Pliskova both took Azarenka to 3 sets.
I expect Serena to be up for this one from the first ball. No underestimation of her opponent in this one. It will be interesting to see how Azarenka performs. She has a slight chance of taking a set but straight sets looks a little more likely.
Back Serena if she is broken first.