Sergio Perez called Sunday’s Malaysian Grand Prix “the hardest race of my career” after battling a virus throughout the weekend that made him think he would need to retire, but rallied to finish sixth.

Perez had been struggling with sickness throughout the race weekend at Sepang, particularly in the lead-up to lights out, but was able to fight his way from P9 on the grid to sixth at the chequered flag.

“It was probably the hardest race of my career, on a weekend in which I feared I would need to give up. It is an amazing result just to make it to the finish,” Perez said.

“I just kept going out of willingness to do it and I have to thank the doctors for helping me out. Having a good start was the key to my race and so was passing [Stoffel] Vandoorne during the first few laps.

“After that, I was able to manage my race and it was all pretty uneventful. We were able to extend the first stint and manage our tyres well. I was only under pressure from [Sebastian] Vettel, but that was not really my fight.

“We scored some more important points for the team and I am happy to come home with a good result after such a difficult weekend.

“I hope to be back to full fitness in Japan.”

Team-mate Esteban Ocon helped Force India extend its advantage over nearest-rival Williams in the constructors’ championship by taking the final point for P10, having been forced to pit early after contact.

“It was a disappointing race and I’m not feeling very happy. The contact on Lap 1 with [Felipe] Massa gave me a puncture and ruined my race,” Ocon said.

“I had to pit on lap two and drive almost the entire race on one set of soft tyres. When you consider the condition of the tyres at the end of the race, we did well to score the final point.

“The other bad moment of my race happened when I was overtaking [Carlos] Sainz and he crashed into me. I shouldn’t have been fighting him, but I was out of position because of the puncture and trying to recover. I don’t know what he did, but he just locked up and went straight into me, causing me to spin.

“So it’s a race to forget for me because the pace of the car was strong and we couldn’t maximise it.”