Hamilton will take the world title, his fourth, this weekend if he wins the race and Vettel finishes outside the top five.
The Brit has been imperious in 2017 in qualifying too, taking 10 poles already, while his German rival has only topped the time-sheets three times on a Saturday.
And he looks set to record yet another pole position at the Circuit of Americas, further extending his record as the best qualifier of all-time in F1.
The race on Sunday will start at 8pm UK time but Saturday’s qualifying session is due to get underway a little later – at 10pm.
US Grand Prix 2017 Q2 results
Eliminated: 11th Felipe Massa (Williams), 12th Daniil Kvyat (Toro Rosso), 13th Stoffel Vandoorne (McLaren), 14th Romain Grosjean (Haas), 15th Nico Hulkenberg (Renault).
With a large engine-related penalty to come tomorrow, it was no surprise that Hulkenberg chose not to put his car out on track again during Q2.
Max Verstappen also had a penalty (15 places) to take and so ran the super-soft as opposed to the ultra-soft tyre so he could start on an alternate strategy tomorrow, but the use of the harder compound did not stop him making it into Q3.
Carlos Sainz briefly looked as though he might fail to deliver on his promising debut Renault practices – but pulled out a fine lap at the last second to get himself up into the top-10 shootout.
US Grand Prix 2017 Q1 results
Eliminated: 16th Marcus Ericsson (Sauber), 17th Lance Stroll (Williams), 18th Brendon Hartley (Toro Rosso), 19th Pascal Wehrlein (Sauber), 20th Kevin Magnussen (Haas).
Not good for Haas on their home race as Romain Grosjean squeezes through by just seven thousandths of a second and Kevin Magnussen is the slowest man on the track.
The most impressive performance comes from Carlos Sainz, on his Renault debut, who slams the big yellow car into fifth place. If the French team were regretting loaning him for next year at any point, they probably aren’t now.