Valtteri Bottas was the “only slight flaw” in Mercedes’ title-winning 2018 campaign, according to Formula 1 sporting boss Ross Brawn.

Mercedes successfully defended both F1 world championships this year to keep up its perfect record of winning every single title on offer during the V6 hybrid era, despite facing stiff competition from Ferrari.

Lewis Hamilton sealed his fifth drivers’ world title in Mexico and rounded off the season with his 11th victory in the Abu Dhabi finale, one race after Mercedes had claimed the constructors’ crown in Brazil. 

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Speaking about Lewis Hamilton and Mercedes’ success in 2018, Brawn highlighted the performance of Bottas, whom he believes was “rather out of sorts” by the end of the season.

“The only slight flaw, if there can be one in a season like this, was the performance of Valtteri Bottas, who had a difficult season, plagued by bad luck,” Brawn said.

“Valtteri had some opportunities to win, but either through misfortune, as in Baku, or due to the occasional, understandable, decision by the team to maximise the result for the benefit of both championships he didn’t manage it.

“The result [was] that he seemed rather out of sorts by the end of the campaign.”

Mercedes’ latest F1 triumph means the German manufacturer has become just the second team after Ferrari (2000-2004) to win five successive world championship doubles.

Brawn acknowledged the “impressive” achievements of the Mercedes team to avoid complacency in its battle with Ferrari.

“When you win so much and for so long, it is very easy to fall into the trap of complacency,” he explained.

“It’s almost inevitable but can be avoided by consistently raising the bar. Only Ferrari in the Schumacher era has won more than five titles in a row and I had the honour of being technical director of the team when they managed six.

“I recall that every year we were aware that for the following season, we would be starting again from zero, aware that just because we had been strong before, it didn’t automatically translate into an advantage of fractions of a second, because in Formula 1, you can never stop.

“That’s what the team run by Toto Wolff was able to do - avoid panic when it realised that it was not enough to be perfect to beat Ferrari but that more effort would be required than had initially been envisaged.”