The duo will start again today at Manchester City.
"It is something I am aware of and I am sure nature will take its own course in time," said Moyes.
"I just feel I had taken over a new job and felt it was important I got a little bit of rhythm.
"I will change players round at different times, but because of the start to the Premier League we had, I made up my mind I was going to keep quite strong in the opening period and then look to see what happens after that.
"Vida and Rio have felt really good through pre-season.
"Their fitness has been great and I think they are both enjoying it."