Red Bull team principal Christian Horner feels Mercedes has become complacent with dominance after witnessing another error that allowed Max Verstappen to claim second place at the Russian Grand Prix.
Lewis Hamilton was given two five-second time penalties for practising his starts in an incorrect position in the pit lane, despite communication with race engineer Pete Bonnington.
After serving the combined 10-second penalty at his one-and-only pit stop, the six-time champion was forced to settle for third behind Verstappen and race-winning team-mate Valtteri Bottas.
With Hamilton and Mercedes also losing a victory courtesy of a penalty for entering a closed pit lane at Monza, Horner believes Mercedes may just be losing its edge after all its years of success.
"We would desperately like to get a car to challenge them," he said. "Operationally, we have a very strong team, we demonstrated that again [at Sochi].
"The last pit stop, if we didn't break the record we were certainly close to it. I got 1.8 seconds on my watch so it will be interesting to see when those timings come out.
"We can only focus on ourselves, they [Mercedes] have had some issues.
"When you are constantly at the front, it is easier sometimes to be the challenger team. Sometimes complacency can slip in with dominance."
Verstappen's second place marked Red Bull's best finish in Sochi, in contrast to team-mate Alex Albon who endured a torrid race and could only finish 10th.
Horner acknowledged another stellar performance from Verstappen. He added: "We know that Max is driving at a very high level.
"His lap, in particular, [in qualifying] was sensational. Again, absolutely no mistakes [in the race] at all. A very mature and measured performance.
"I think Mercedes had a faster car than us during the weekend. We benefitted from Lewis' penalty but I think Max has just extracted every ounce of performance out of the car throughout.
"Our best result here in the six years we have been coming so pleased with the drive of Max."
Before you go...
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Hamilton and Mercedes to race "squeaky clean" to avoid future punishment
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