Valtteri Bottas has admitted that Mercedes struggled with some balance issues in their new 2019 car over testing this week, even calling some of the issues "massive", but remains upbeat that any problems can be solved as long as the team keep working hard.
In testing at the Circuit de Catalunya, Lewis Hamilton and Bottas largely kept a low profile, with Ferrari stealing headlines with their pace and amount of laps on the track.
The Finn has claimed that this is down to the team focusing on car development, as the two drivers suffered with balance at certain corners.
"We have work to do, but it’s a good feeling in the sense that it feels like there is potential," Bottas said.
"We do need to make improvements. We were struggling a bit over the week to find a good balance for all the corners.
"There were some corners that were good, some corners we would have balance issues and other corners we would have massive balance issues."
As the days progressed in testing, the Silver Arrows' performance improved, but Bottas says the team needs to continue to address any faults, even if it means an upgrade.
"We were getting to a much better state at the end of the week, but some of the handling issues can only be sorted with some upgrades. We’re hoping to fix those hopefully soon," he added.