The opening timesheet of the title-deciding weekend was skewed somewhat by teams having access to an additional set of tyres, Pirelli bringing prototype versions of the softer tyres they intend to introduce next season.
The majority of drivers duly tried the one-off orange-marked rubber out in the opening stages of the session and it was during this period when Hamilton set what would stand as the fastest time of the morning, 1:14.131.
World Championship leader Sebastian Vettel was already within a tenth of the McLaren's pace on the same rubber but later went even quicker on the definitive hard compound to be used this weekend, lapping a mere 0.009s slower than Hamilton.
Indeed, underlining the competitiveness of both McLaren and Red Bull, the top two's respective team-mates were also within a tenth of the benchmark lap with Mark Webber third, also on the 2012 tyre, and Jenson Button fourth on the 2013 rubber.
Underlining his seemingly ever-growing status as Ferrari's team leader, Fernando Alonso left team-mate Felipe Massa to do the donkey work on the 2013 rubber as he sat out the early stages although did eventually try the development tyre right at the end and consolidated fifth on his final lap, 0.261s off the pace.
Massa ended up sixth in the sister Ferrari, half a second back, ahead of the lead Lotus of Roimain Grosjean as the other of Kimi Raikkonen ran into engine difficulties.
Williams's Pastor Maldonado was sandwiched between the two Force Indias of Paul di Resta and Nico Hulkenberg at the bottom of the top ten.
With the championship to be decided at Interlagos on Sunday, all eyes had been on the amount of upgrades, if any, either protagonists Red Bull and Ferrari had brought to their cars to aid their respective challenger's assault.
As revealed by Sky Sports F1's Ted Kravitz early on Friday, the former had flown in new parts from London overnight with the package including new rear wing and bodywork for the RB8 - although at the start of P1 Red Bull had been trying back-to-back tests with a combination of parts from Austin and previous races.
Ferrari, by contrast, have brought a new front wing to the title showdown and Alonso duly tried it out in P1, with the early results appearing to be positive for the Scuderia as they made a last-ditch attempt to close their single-lap deficit to Red Bull and McLaren.