The car that earned Nico Rosberg his second career pole at the Bahrain Grand Prix never showed up on race day.
He was passed with ease by race winner Sebastian Vettel on the second lap and never recovered. Lacking the pace of the Lotus and even Force India, he quickly fell down the grid and finished a disappointing ninth. The only other time he claimed pole, at the Chinese GP, he won the race.
"A tough day for me," Rosberg said. "As nice as it was to start from pole this afternoon, it was just as hard to finish in ninth place. I didn't feel comfortable in the car today and it wasn't much fun out there really."
Rosberg said the team switched to a four-stop strategy but that still didn't help his performance.
"We were using the rear tyres too much and at the end, I was really struggling and wasn't able to push hard enough," he said. "There is a lot of work ahead and we need to focus on why our race performance isn't matching the pace that we can show in qualifying. Hopefully we can make some steps here before the European season starts."
It was the opposite story for teammate Lewis Hamilton, who started ninth due to a five-place grid penalty for changing a gear box ahead of qualifying. He dropped to tenth after a poor start but fought his way up the grid and passed Red Bull's Mark Webber on the final lap to claim fifth.
Hamilton made a much-criticised switch from McLaren to Mercedes in the off-season, with many pundits suggesting he wouldn't challenge for the driver's championship again. Instead, the 2008 champion has had two third-place finishes and was on pole in China.
"It's been a tough weekend for us but we got through it and finishing in fifth place was some good damage limitation," Hamilton said. "My race didn't start well at all. I was looking after the tyres but I really struggled on the first two stints and was falling back. But as the temperatures dropped, the car picked up and then I had the grip that I needed to push and close the gap. I'm very proud of what we have achieved over the first four races and to be third in the drivers' championship is beyond any of our expectations."
The team's executive director, Toto Wolff, said the team will now work ahead of the next race in Barcelona to figure out why it had such troubles in the hot track conditions of Bahrain.
"We knew it would be a tough day and the high track temperatures were clearly not good for us. That's not an excuse but a priority area to improve," he said. "We need to analyse carefully why we suffered so much, particularly in the early stages, and why we were not on the pace. ... We learned a lot this afternoon but it is clear that we still have a lot to learn."