"Marina and I played a couple of times and it's always a tough match," Muguruza said in her on-court interview. "I'm happy, even with my body, that I won. It was very tough."
Earlier in the season in Brisbane, Muguruza was forced to retire from her semifinal against Alizé Cornet due to a right thigh injury, and it seemed like the pain still lingered in her Melbourne opener.
Despite taking a close opening set, Muguruza's movement appeared to be hampered and she struggled with her timing, her usually powerful groundstrokes at times lacking their bite.
The Spaniard's problems multiplied in the second set, as Erakovic took every opportunity Muguruza's condition handed her and went up a 4-1 lead.
"It was very tough. You're playing, then suddenly you start to feel pain in your body," Muguruza explained. "Obviously I was nervous, so I just tried to be calm, to have a good attitude and keep fighting for the match."
The New Zealander wasn't able to hang on to that lead for very long, as Muguruza - with great effort - came roaring back. Erakovic seemed to lose her confidence as Muguruza climbed back up the scoreboard, finally rattling off five straight games to take the match.