Mercedes engineering director Andrew Shovlin has stated that the team's data from the 2021 pre-season test shows they are not as fast as Red Bull and could have difficulty in making up the deficit.
The Silver Arrows endured some uncharacteristically challenging moments during testing in Bahrain and now have concerns that they are being beaten on race pace by Max Verstappen's team as well as others.
"We’ve made a bit of progress with the balance on higher fuel and the car was more predictable but we can see from the data we’ve collected over the last few days that on race pace, we’re not as quick as Red Bull," Shovlin said in a statement from Mercedes at the end of Day Three.
"The lower fuel work was a more confusing picture, we didn’t gain enough and we need to go and look at our approach as far too many cars were ahead of us on pace today. We’ve had issues in recent years with pace in winter testing and managed to make good progress before the first race but we may have our work cut out this time."
With the opening race of the 2021 F1 season set to take place in Bahrain on 28 March, Mercedes now face a race against time to resolve their issues.
Shovlin said: "We’ve not got long before we’re back here for the race so we’ve planned a programme of work to try and understand some of our issues and will be leaving no stone unturned in our efforts to find some more speed over the next ten days."
Mercedes finished the final day of testing with Lewis Hamilton in fifth place on the timesheets whilst Valtteri Bottas ended up in 16th. Despite the team's problems, Shovlin still feels that there were some positives from what they managed to achieve.
"We’ve had another day with good reliability where we were able to run to plan throughout the day," he explained. "Valtteri was doing long run setup work in the morning and Lewis doing a mix of long run work and qualifying work in the afternoon."