City's Bernardo Silva and Mateo Kovacic both misfired in the shootout to put Madrid in the driving seat
The Russian world number four made the announcement on her Facebook page on Thursday after being without a coach since parting ways with Jimmy Connors in August.
Connors lasted just a month after joining the 26-year-old following the Wimbledon tournament in July.
"I'm happy to announce my official partnership with Sven Groeneveld," Sharapova wrote.
"We've been working together since I got back on the court and after seeing him on the opposing side for so many years, I'm excited to have him become a part of my team.
"It has been a very seamless transition and I have had a lot of fun with the hard work we have put in so far. Looking forward to the year ahead."