Keys won both their previous matches. Their last meeting was on the grass in Birmingham in June this year. She won in a 3rd set tie break. The other match was on a hard court in 2013 in Tokyo. She won in 3 sets.
Both are having good seasons. Suarez Navarro had a good win over Ivanovic in the 1st round and a tight straight sets win over Konjuh. She has done well in big tournaments this season and won a hard court title in February in Doha.
Keys had an easy 1st match but had to work very hard against Mladenovic. She won that one in a 3rd set tie break.
Keys reached the final in Montreal 2 weeks ago. She has had almost a week to recover but may be feeling the effects of that week when she played 6 matches.
As both of their previous matches went to 3 sets and Keys may be tiring I see value on Suarez Navarro.
Lay Keys around 1.25 to 1.30