Rybakina, who won the championship in 2022, lost her first game of the match as she sought to find her big-serving rhythm.
The fourth seed, from Kazakhstan, has had illness and fitness problems recently but looked more comfortable as the match progressed and clinched the first set with a thumping serve that Ruse could only put wide.
Ruse, who qualified last week without dropping a set, was already faltering under the barrage of heavy groundstrokes when she slipped and needed treatment in the second set.
She resumed, but Rybakina, who leads the women's tour stats for aces this year with 270, wrapped up the match in an hour and 11 minutes on her second match point.
"Really happy to win my first match here this year. I didn’t play on grass too much this year because I’ve had some issues," Rybakina said in an interview on court.
"I’m just keeping all the emotions inside, sometimes it’s not easy but I’m looking forward to the next one. I just want to be happy on the court, that’s my goal now."