Lewis Hamilton cannot afford to be complacent in his attempt to win a fourth Formula One world championship despite a 28-point lead, warned Toto Wolff, the Mercedes executive director. Hamilton won the Singapore Grand Prix on Sunday after his title rival Sebastian Vettel crashed his Ferrari off the grid and was eliminated from the race.

Hamilton had gone into the race leading Vettel by three points but had expected to drop behind the German at a circuit where Ferrari were hoping to dominate. However, Vettel went out after the incident involving his team-mate Kimi Raikkonen and Red Bull’s Max Verstappen on the run to turn one, with all three retiring. The win, Hamilton’s third in a row, has given the British driver a commanding lead with six races to go.

Wolff said he expected his driver and team to remain fully focused for the rest of the season. “I would expect him to not let up, you cannot let up, there are six more races to go,” he said. “We must not drop the ball, we would not feel comfortable in Ferrari’s shoes having a 28-point deficit but we must get on with the job. There’s lots of time for cheering when we’ve actually won the title.”

The advantage the 32-year-old holds is enough for him to endure a race without points and maintain the lead. But the team are acutely aware that a retirement would still be a major blow. The next round is at Malaysia, a race in which Hamilton was leading last year when he endured an engine failure, after which Nico Rosberg went on to take the championship.

Wolff noted that the events in Singapore only highlighted how quickly the pendulum can swing in F1. “You don’t know what is in front of you,” he said. “Six more races means it can go against us six times, in a similar way in that it went against Ferrari. So you have to concentrate and optimise the result.”

Hamilton drove an impressive race to win at Marina Bay, overcoming difficult, wet conditions and repeated safety car interruptions and had little time for a fan who had claimed the German was the better driver. He addressed the suggestion on Instagram. “One day you will see that that’s not the case,” he said. “If you haven’t, then maybe you need to go to Specsavers.”

Wolff also believed his driver was making the difference. “On a difficult day you would like Lewis in the car,” he said. “Singapore was a good example of that, where there was more chance of making a mistake than driving it home.” He was also adamant that although he had sympathy for Ferrari, there would be no let up in the title fight. “You can kind of feel for Ferrari,” he said. “I’ve been in the situation of losing both cars, and you can relate how awful that feels for them. But we’re not here to take prisoners.”

The majority of the remaining six races should favour the Mercedes but Hamilton was taking nothing for granted. Assessing the forthcoming grands prix he believed Ferrari would remain strong. “We have Malaysia, where I think we should be OK,” he said. “Then we have Japan, high downforce circuit; could be close, it definitely won’t be our strongest. Austin, I think we’ll be fine. I think Brazil would be a place where Ferrari will be particularly strong. Honestly, I think it’s going to be very close in the next races. It’s hard to predict. When you go to Mexico, you put your maximum downforce on but because it’s so high there’s little drag and maybe the cars that have a little bit more downforce might just have the edge on us.”

The win takes Hamilton to 60 grand prix victories. Only Michael Schumacher has more, with 91, although he stressed beating the German’s record was not his priority. “I’m loving driving more than ever,” he said. “I feel like I am driving better than ever, and I feel the most whole as a driver that I have ever been which is a great feeling.

“Who knows if we are going to get anywhere near Michael Schumacher’s record of seven championships? I don’t have a desire to chase that, but records are there to be broken so at some stage someone will break them. Whether it is me, I can’t tell you.”