Max Verstappen could wrap up a second consecutive title with a victory in Singapore next month after winning 11 races of out of 16 this season.
When asked if Red Bull could run the table over the final weeks of the campaign, Horner told Autosport, "that’s a massive ask and (there is) some huge variance of circuits.
"Singapore compared to Monza, it’s got the most corners on the calendar. It’s bumpy, it’s a street track, so it’s a much different challenge," the Briton added in the interview published on Monday.
"We’re in a great position in the championship. But we’re going to attack every race and do the best we can, then the points will take care of themselves.
"But you know, we’ve been quick at Spa, Zandvoort, Monza and Budapest even. So on a variance of circuits, the car’s performing really well."
The title battle will be over on October 2 if Verstappen scores 22 more points than Ferrari’s Charles Leclerc, his closest rival, in the next race under floodlights in Singapore.
Additional reporting from PA