Vesnina 1.81 ,Mertens 2.22
Mertens won their only previous meeting. That was in April this year in a Federation Cup tie in Russia. Mertens won on clay in 3 sets.
Mertens has better overall results this season. Her ROI is higher too. On hard courts she also has a slight edge but there isn’t a huge gap between them. She has won 66% of her matches on this surface compared to 60% for Vesnina. They both have a very healthy ROI.
Mertens needed 3 sets to beat Naomi Osaka in the last round though she started the match as slight underdog She reached the quarter finals in Tokyo a couple of weeks ago and the semi finals in New Haven on August as a qualifier.
Vesnina won the title in Indian Wells in March but has struggled to find consistency on hard courts since other than a third round finish at the US Open in August. She beat Ying Ying Duan in straight set sin the last round but will need to serve better today. She hit 8 double faults in that match.
We have value on Mertens as market underdog to take at least a set. Lay Vesnina if she breaks first and remove liability if she then gets broken herself.
Update: Vesnina won in straight sets. She played well but Mertens was disappointing