"A tough day," the New Zealander said. "We expected there to be some challenges this morning. I certainly under-estimated the mental challenge of getting back in car in competition and everything really felt abnormal on the morning loop.
"I sat with my engineer Rui at lunch and we made some changes to the car to make it easier to drive, not necessarily changes to make it faster, just to get some confidence back in.
"The afternoon was certainly a big step in the right direction. Things don't quite feel 100% yet. "We're working on it piece by piece, but the feeling's starting to come back and we're starting to enjoy it this afternoon. Gives us something really good to build on going into tomorrow.
"I think we can start our season proper tomorrow. I'll get in the car with a lot more confidence with a set-up that's working and try to get a bit of momentum on our way."
Seven further stages await on day two, beginning tonight, with three more tomorrow night.
Standings after day 1
1. Thierry Neuville (Hyundai)
2. Jari-Matti Latvala (Toyota) +28.1s
3. Ott Tanak (Ford) +49.7s
4. Kris Meeke (Citroen) +51.8s
5. Sebastien Ogier (Ford) +55.7s
6. Hayden Paddon (Hyundai) +1:17.8s
7. Dani Sordo (Hyundai) +1:40.3s
8. Craig Breen (Citroen) +1:54.3s
9. Elfyn Evans (Ford) +3:01.5s
10. Stephane Lefebvre (Citroen) +3:23.6s