Paul di Resta believes Force India can target Sauber's sixth place in the F1 standings

The Scotsman produced a strong drive in the Singapore Grand Prix to finish fourth, right behind championship leader Fernando Alonso.

Force India's recent form has led some to suggest it could even be a threat to Mercedes, but di Resta is more cautious due to the 61-point gap between the two British-based teams.

"I think fifth in all honesty is out of reach," di Resta told AUTOSPORT. "It would take a lot of bad luck for them and for us a lot of good luck, but I'm not going to say we're giving up because you can see what we can do.

"We just have to keep plugging away but sixth should be a good ask for us. Williams [eighth in the standings] are obviously showing strong signs as well."

Force India is currently seventh in the constructors' table, 26 points behind Sauber. It is now 21 points ahead of Williams, which again failed to score any points in Singapore.

Di Resta's caution about Force India's prospects is also based on the fact that he does not expect the team to be as strong at the next race in Japan.

"If there is any track that could show up our weaknesses then it is Suzuka," he said. "This [Singapore] is a bit special as there are more bumps and kerbs to contend with.

"I'd like to think it will be the same with the next one but I'm not going to commit. I'll stand at the back like I was on Friday here. I have not been on the simulator yet so I will work hard and see if we can achieve the maximum we can."