Lewis Hamilton was looking in very strong form in Monaco on Friday for both of the Friday practice sessions which saw him fastest of all in FP1 and second quickest behind Charles Leclerc in FP2.
Hamilton is hoping that this time they will able to carry their Friday form through to the rest of the weekend, rather than having their rivals overtake them in qualifying and race trim.
"It's been a good day, probably the best we've had so far this year," he said after the end of today's track sessions. "The car is feeling very positive.
"This track is just amazing in an F1 car, and I've been enjoying my driving today," he continued. " I was pleasantly surprised by the grip level and the way the car was responding."
He said that it "made it a much more enjoyable ride than the last two years," suggesting real progress with this year's W15 compared with its 'prima donna predecessors since the return of ground effect aerodynamics.
However Hamilton admitted the situation had got trickier in the afternoon compared to FP1.
"In the second session it felt a bit less comfortable," he said. "We've got lots of work to do overnight to improve the long runs and the front graining.
"It was a feeling positive on the lower fuel, and we don't want to lose that, but our focus now is to improve on the long run," he added.
Team mate George Russell was third in the first session but dropped to P10 in the later practice as he battled with his steering wheel, although he didn't sound too concerned about it for the rest of the weekend.
"My session was limited by the steering vibration," he confirmed. "As soon as I touched the brakes, the steering system was shaking, and on a track like this where you need confidence to attack, that really set me back.
"But that was one of our best Fridays of the year, and the car is feeling the best I've ever had in Monaco," he insisted. "The car is feeling good, and Lewis's times showed the performance that's in there.
"But Charles is very quick, and we know as well how quickly things can change," he acknowledged. "Every team is developing so quickly, and you can see how much faster the lap times are this year than last.
Asked what he was hoping for in qualifying, Russell said: "I hope we will be fighting for the top five tomorrow."
Mercedes' Trackside Engineering Director Andrew Shovlin described it as "a pretty good day with both cars" despite the problems on Russell's car.
"George was struggling with a vibration on braking - we need to get on top of that for tomorrow as it appeared to get worse during the course of the day and was very intrusive this afternoon.
"However the underlying pace of the car seems good. Our long run needs some work as we've got to be a bit kinder on the front tyres on Sunday but we've got some options for that."
Shovlin said the team had brought forward its use of the soft tyres to FP1 because of concerns about rain later in the day, which ultimately never materialised.
"It meant we were on used tyres for the low fuel soft in the afternoon," he said, explaining why Hamilton wasn't able to keep up the pace with Leclerc.
"We've also got to track the circuit as the grip comes up but it's encouraging that we seem to have a decent platform to work from."
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