The world number five overcame Czech talent Tereza Martincova 6-4, 4-6, 6-3 in two hours and 45 on court.

After seeing out the opening set, Muguruza exchanged five breaks with Martincova in the second before the Czech levelled the match.

After trading breaks to open the decider, Muguruza secured a double break to close out the match.

The 28-year-old is making her debut at the WTA 500 event this year. This is her first WTA victory on Russian soil.

She now moves on to the quarter-finals as she looks to add to her tour titles in Dubai and Chicago this season.

The tournament is also an opportunity to consolidate her push to the season-ending WTA Finals.

The Spaniard currently sits seventh in the Porsche Race to the WTA Finals, closely followed by compatriot and Indian Wells champion Paula Badosa.

Muguruza has qualified for the Finals on three occasions, in 2015, 2016 and 2017, the latter two being the same years she captured her French Open and Wimbledon titles respectively.

Should she win her next match against either Andrea Petkovic or ninth seed Anett Kontaveit, she should accrue enough ranking points to cement her spot at the event in Guadalajara, Mexico.